CRC Handbook of Basic Tables for Chemical Analysis, Second Edition

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HANDBOOK of

BASIC TABLES for

CHEMICAL ANALYSIS Second Edition

Thomas J. Bruno Paris D.N. Svoronos

CRC PR E S S Boca Raton London New York Washington, D.C.

Copyright © 2003 CRC Press, LLC

1573_C00.fm Page iv Tuesday, November 25, 2003 11:40 AM

Library of Congress Cataloging-in-Publication Data Bruno, Thomas J. Handbook of basic tables for chemical analysis/authors, Thomas J. Bruno, Paris D.N. Svoronos—2nd ed. p. cm. Rev. ed. of: CRC handbook of basic tables for chemical analysis, c1989 Includes bibliographical references and index. ISBN 0-8493-1573-5 (alk. paper) 1. Chemistry, Analytic—Tables, I. Svoronos, Paris D. N. II. Bruno, Thomas J. CRC handbook of basic tables for chemical analysis, III. Title. QD78.B78 2003 543′.002′1—dc22 2003055806 CIP

This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage or retrieval system, without prior permission in writing from the publisher. The consent of CRC Press LLC does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from CRC Press LLC for such copying. Direct all inquiries to CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. Certain commercial equipment, instruments, or materials are identified in this handbook in order to provide an adequate description. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, the City University of New York, or Georgetown University, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose. The authors, publishers, and their respective institutions are not responsible for the use of which this handbook is made. Occasional use is made of non-SI units, in order to conform to the standard and accepted practice in modern analytical chemistry.

Visit the CRC Press Web site at www.crcpress.com Not subject to copyright in the United States No claim to original U.S. Government works International Standard Book Number 0-8493-1573-5 Library of Congress Card Number 2003055806 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Printed on acid-free paper


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Dedication We dedicate this work to our children, Kelly-Anne, Alexandra, and Theodore.


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Preface to the First Edition This work began as a slim booklet prepared by one of the authors (T.J.B.) to accompany a course on chemical instrumentation presented at the National Institute of Standards and Technology, Boulder Laboratories. The booklet contained tables on chromatography, spectroscopy, and chemical (wet) methods, and was intended to provide the students with enough basic data to design their own analytical methods and procedures. Shortly thereafter, with the co-authorship of Professor Paris D.N. Svoronos, it was expanded into a more extensive compilation entitled Basic Tables for Chemical Analysis, published as a National Institute of Standards and Technology Technical Note (number 1096). That work has now been expanded and updated into the present body of tables. Although there have been considerable changes since the first version of these tables, the aim has remained essentially the same. We have tried to provide a single source of information for those practicing scientists and research students who must use various aspects of chemical analysis in their work. In this respect, it is geared less toward the researcher in analytical chemistry than to those practitioners in other chemical disciplines who must make routine use of chemical analysis. We have given special emphasis to those “instrumental techniques” that are most useful in solving common analytical problems. In many cases, the tables contain information gleaned from the most current research papers, and provide data not easily obtainable elsewhere. In some cases, data are presented that are not available at all in other sources. An example is the section covering supercritical fluid chromatography, in which a tabular P-ρ-T surface for carbon dioxide has been calculated (specifically for this work) using an accurate equation of state. While the authors have endeavored to include data, which they perceive to be most useful, there will undoubtedly be areas that have been slighted. We therefore ask you, the user, to assist us in this regard by informing the corresponding author (T.J.B.) of any topics or tables that should be included in future editions. The authors acknowledge some individuals who have been of great help during the preparation of this work. Stephanie Outcalt and Juli Schroeder, chemical engineers at the National Institute of Standards and Technology, provided invaluable assistance in searching the literature and compiling a good deal of the data included in this book. Teresa Yenser, manager of the NIST word processing facility, provided excellent copy despite occasional disorganization on the part of the authors. We owe a great debt to our board of reviewers, who provided insightful comments on the manuscript: Profs. D.W. Armstrong, S. Chandrasegaran, G.D. Christian, D. Crist, C.F. Hammer, K. Nakanishi, C.F. Poole, E. Sarlo, Drs. R. Barkley, W. Egan, D.G. Friend, S. Ghayourmanesh, J.W. King, M.L. Loftus, J.E. Mayrath, G.W.A. Milne, R. Reinhardt, R. Tatken, and D. Wingeleth. The authors acknowledge the financial support of the Gas Research Institute and the United States Department of Energy, Office of Basic Energy Sciences (T.J.B.) and the National Science Foundation, and the City University of New York (P.D.N.S.). Finally, we must thank our wives, Clare and Soraya, for their patience throughout the period of hard work and late nights.


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Preface to the Second Edition Some 15 years have elapsed since the publication of the first edition of the CRC Handbook of Basic Tables for Chemical Analysis. Since that time, many advances have taken place in the fields of chemical analysis. Because of these advances, the second edition is considerably expanded from the first. We consider this revision unique in that it features to a large extent the input of users of the first edition. In the preface of the first edition, we requested that users contact us with suggestions and additions for the present volume. Over the years, we have gotten many excellent suggestions, for which we are grateful. In many respects, this volume is a result of user input, as well as the efforts of researchers in analytical chemistry who have advanced the field. The user will find in this volume many new tables and several new chapters. We have added a chapter on electrophoresis and one on electroanalytical methods. The section on gas chromatography has been expanded to include the modern methods of solid phase microextraction (SPME) and head space analysis in general, and also new information on detector optimization. The stationary phase tables have been revised. We have deliberately chosen to leave information of historical significance. Thus, while many of the gas chromatographic stationary phases presented for packed columns are not often used today, inclusion of such information in this volume will make it easier to interpret the literature. The section on high-performance liquid chromatography has been updated with the most recent chiral stationary phases, detector information, and revised solvent tables. The tables on spectroscopy have been significantly expanded as well, and in some cases, we have adopted different presentation formats that we hope will be more useful. The miscellaneous tables present in the first edition have been expanded and have in fact spawned two new chapters: “Solutions Properties” and “Tables for Laboratory Safety.” In “Solution Properties,” we collect in one place information on organic and inorganic solvents and mixtures used in chemical analysis. Reflecting the growing emphasis on laboratory safety, this topic is now treated far more in depth in “Tables for Laboratory Safety.” We provide information on many kinds of chemical hazards and electrical hazards in the analytical laboratory, and information to aid the user in selecting laboratory gloves, apparel, and respirators. This aspect of the book is unique, since no other handbook of analytical chemistry provides a selfcontained source of information that covers not only carrying out a lab procedure, but also carrying it out safely. Our philosophy in preparing this book has been to include information that will help the user make decisions. In this respect, we envision each table to be something the user will consult when reaching a decision point in designing an analysis or interpreting results. We have deliberately chosen to exclude information that is merely interesting, but of little value at a decision point. Similarly, it has occasionally been difficult to strike an appropriate balance between presenting information that is of general utility and information that is highly specific and perhaps simply a repetition of what is contained in vendor catalogs, promotional brochures, and websites. In this respect, we have tried to keep the content as generic and unbiased as possible. Thus, some specific chromatographic phases and columns, available only under trade names, have been excluded. This must not be regarded as a value judgment, but simply a reflection of our philosophy.


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Acknowledgments The authors acknowledge some individuals who have been of great help during the preparation of this work. Marilyn Yetzbacher of NIST prepared the artwork used throughout this volume. Lorene Celano, also of NIST, prepared many of the tables in the revision. Without the help of these two individuals, this volume could never have been completed. As before, we owe a great debt to our board of reviewers: Profs. M. Jensen, A.F. Lagalante, D.C. Locke, K.E. Miller, Drs. W.C. Andersen, D.G. Friend, S. Ghayourmanesh, A.M. Harvey, M.L. Huber, D. Joshi, M.O. McLinden, S. Ringen, S. Rudge, M.M. Schantz, and D. Smith. Finally, we must again thank our wives, Clare and Soraya, and our children, Kelly-Anne, Alexandra, and Theodore, for their patience and support throughout the period of hard work and late nights.


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The Authors Thomas J. Bruno, Ph.D., is a project leader in the Physical and Chemical Properties Division at the National Institute of Standards and Technology, Boulder, CO. He is also on the adjunct faculty in the Department of Chemical Engineering at the Colorado School of Mines. Dr. Bruno received his B.S. in chemistry from the Polytechnic Institute of Brooklyn, and his M.S. and Ph.D. in physical chemistry from Georgetown University. He served as a National Academy of Sciences–National Research Council postdoctoral associate at NIST, and was later appointed to the staff. Dr. Bruno has done research on properties of fuel mixtures, chemically reacting fluids, and environmental pollutants. He is also involved in research on supercritical fluid extraction and chromatography of bioproducts, the development of novel analytical methods for environmental contaminants and alternative refrigerants, and novel detection devices for chromatography, and he manages the division analytical chemistry laboratory. In his research areas, he has published approximately 115 papers and 5 books and holds 10 patents. He was awarded the Department of Commerce Bronze Medal in 1986 for his work on the thermophysics of reacting fluids. He has served as a forensic consultant and an expert witness for the U.S. Department of Justice (DOJ), and received in 2002 a letter of commendation from the DOJ for these efforts. Paris D.N. Svoronos, Ph.D., is professor of chemistry and department chair at QCC of the City University of New York. In addition, he holds a continuing appointment as visiting professor in the Department of Chemistry at Georgetown University. Dr. Svoronos obtained a B.S. in chemistry and a B.S. in physics at the American University of Cairo, and his M.S. and Ph.D. in organic chemistry at Georgetown University. Among his research interests are synthetic sulfur and natural product chemistry, organic electrochemistry, and organic structure determination and trace analysis. He also maintains a keen interest in chemical education and has authored several widely used laboratory manuals used at the undergraduate levels. In his fields of interest, he has approximately 70 publications. He has been in the Who’s Who of America’s Teachers three times in the last five years. He is particularly proud of his students’ successes in research presentations, paper publications, and professional accomplishments. He was selected as the 2003 Professor of the Year by the CASE (Council for the Advancement and Support of Education) committee of the Carnegie Foundation.


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Contents Chapter 1 Gas Chromatography Chapter 2 High-Performance Liquid Chromatography Chapter 3 Thin-Layer Chromatography Chapter 4 Supercritical Fluid Extraction and Chromatography Chapter 5 Electrophoresis Chapter 6 Electroanalytical Methods Chapter 7 Ultraviolet Spectrophotometry Chapter 8 Infrared Spectrophotometry Chapter 9 Nuclear Magnetic Resonance Spectroscopy Chapter 10 Mass Spectrometry Chapter 11 Atomic Absorption Spectrometry Chapter 12 Qualitative Tests Chapter 13 Solution Properties Chapter 14 Tables for Laboratory Safety Chapter 15 Miscellaneous Tables


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CHAPTER

1

Gas Chromatography CONTENTS Carrier Gas Properties Carrier Gas Viscosity Gas Chromatographic Support Materials for Packed Columns Mesh Sizes and Particle Diameters Packed Column Support Modifiers Properties of Chromatographic Column Materials Properties of Some Liquid Phases for Packed Columns Stationary Phases for Packed Column Gas Chromatography Adsorbents for Gas–Solid Chromatography Porous Polymer Phases Relative Retention on Some Haysep Porous Polymers Silicone Liquid Phases Mesogenic Stationary Phases Trapping Sorbents Sorbents for the Separation of Volatile Inorganic Species Activated Carbon as a Trapping Sorbent for Trace Metals Reagent Impregnated Resins as Trapping Sorbents for Trace Minerals Reagent Impregnated Foams as Trapping Sorbents for Inorganic Species Chelating Agents for the Analysis of Inorganics by Gas Chromatography Bonded Phase Modified Silica Substrates for Solid Phase Extraction Solid Phase Microextraction Sorbents Extraction Capability of Solid Phase Microextraction Sorbents Salting Out Reagents for Headspace Analysis Partition Coefficients of Common Fluids in Air–Water Systems Vapor Pressure and Density of Saturated Water Vapor Derivatizing Reagents for Gas Chromatography Detectors for Gas Chromatography Recommended Operating Ranges for Hot Wire Thermal Conductivity Detectors Chemical Compatibility of Thermal Conductivity Detector Wires Data for the Operation of Gas Density Detectors Phase Ratio for Capillary Columns Martin–James Compressibility Factor and Giddings Plate Height Correction Factor Cryogens for Subambient Temperature Gas Chromatography Dew Point–Moisture Content



CARRIER GAS PROPERTIES The following table gives the properties of common gas chromatographic carrier gases. These properties are those used most often in designing separation and optimizing detector performance. The density values are determined at 0°C and 0.101 MPa (760 torr).1 The thermal conductivity values, λ, are determined at 48.9°C (120°F).1 The viscosity values are determined at the temperatures listed and at 0.101 MPa (760 torr).1 The heat capacity (constant pressure) values are determined at 15°C and 0.101 MPa (750 torr).2

REFERENCES 1. Lide, D.R., Ed., Handbook of Chemistry and Physics, 83rd ed., CRC Press, Boca Raton, FL, 2002. 2. Dal Nogare, S. and Juvet, R.S., Gas–Liquid Chromatography: Theory and Practice, John Wiley & Sons (Interscience), New York, 1962.


Thermal Conductivity Differences, W/(m·K) δλ (He) δλ (N2) δλ (Ar)

Carrier Gas

Density (kg/m3)

Thermal Conductivity × 10–2, W/(m·K)

Hydrogen

0.08988

19.71

3.97

16.96

17.81

0.876 (20.7°C) 1.086 (129.4°C) 1.381 (299.0°C)

14112.7

2.016

Helium

0.17847

15.74

—

12.99

13.84

1.941 (20.0°C) 2.281 (100.0°C) 2.672 (200.0°C)

5330.6

4.003

Methane

0.71680

3.74

−12.00

0.99

1.84

1.087 (20.0°C) 1.331 (100.0°C) 1.605 (200.5°C)

2217.2

16.04

Oxygen

1.42904

2.85

−12.89

0.10

0.95

2.018 (19.1°C) 2.568 (127.7°C) 3.017 (227.0°C)

915.3

32.00

Nitrogen

1.25055

2.75

−12.99

—

0.85

1.781 (27.4°C) 2.191 (127.2°C) 2.559 (226.7°C)

1030.5

28.016

Carbon monoxide

1.25040

2.67

−13.07

−0.08

0.77

1.753 (21.7°C) 2.183 (126.7°C) 2.548 (227.0°C)

1030.7

28.01

Ethane

1.35660

2.44

−13.30

−0.31

0.54

0.901 (17.2°C) 1.143 (100.4°C) 1.409 (200.3°C)

1614.0

30.07

Ethene

1.26040

2.30

−13.44

−0.45

0.40

1.008 (20.0°C) 1.257 (100.0°C) 1.541 (200.0°C)

—

28.05

Propane

2.00960

2.03

−13.71

−0.72

0.13

0.795 (17.9°C) 1.009 (100.4°C) 1.253 (199.3°C)

—

44.09

Argon

1.78370

1.90

−13.84

−0.85

—

2.217 (20.0°C) 2.695 (100.0°C) 3.223 (200.0°C)

523.7

39.94

Carbon dioxide

1.97690

1.83

−13.91

−0.92

−0.07

1.480 (20.0°C) 1.861 (99.1°C) 2.221 (182.4°C)

836.6

44.01

2.51900

1.82

−13.92

−0.93

−0.08

0.840 (14.7°C)

—

650(20°C)

1.63

−14.11

−1.12

−0.27

1.450 (21.1°C)

674.0

n-butane Sulfur hexafluoride


Viscosity × 10−5 (Pa·s)

Heat Capacity (J/(kg·K))

Relative Molecular Mass

58.12 146.05


Carrier Gas Properties


CARRIER GAS VISCOSITY The following table provides the viscosity of common carrier gases, in µPa·sec, used in gas chromatography.1,2 The values were obtained with a corresponding states approach with highaccuracy equations of state for each fluid. Carrier gas viscosity is an important consideration in efficiency and in the interpretation of flow rate data as a function of temperature. In these tables, the temperature, T, is presented in °C, and the pressure, P, is given in kilopascals and in pounds per square inch (absolute). To obtain the gauge pressure (that is, the pressure displayed on the instrument panel of a gas chromatograph), one must subtract the atmospheric pressure. Following the table, the data are presented graphically. REFERENCES 1. Lemmon, E.W., Peskin, A.P., McLinden, M.O., and Friend, D.G., Thermodynamic and Transport Properties of Pure Fluids, NIST Standard Reference Database 12, Version 5.0, National Institute of Standards and Technology, Gaithersburg, MD, 2000. 2. Lemmon, E.W., McLinden, M.O., and Huber, M.L., REFPROP, Reference Fluid Thermodynamic and Transport Properties, NIST Standard Reference Database 23, Version 7, National Institute of Standards and Technology, Gaithersburg, MD, 2002. Carrier Gas Viscosity T, °C

He

H2

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300

18.699 19.163 19.621 20.076 20.527 20.974 21.418 21.858 22.294 22.727 23.157 23.583 24.007 24.427 24.845 25.26 25.672 26.082 26.489 26.894 27.296 27.696 28.094 28.49 28.883 29.274 29.664 30.051 30.436 30.82 31.201

8.3996 8.6088 8.8154 9.0197 9.2218 9.4216 9.6194 9.8152 10.009 10.201 10.391 10.58 10.767 10.952 11.136 11.318 11.498 11.678 11.856 12.033 12.208 12.382 12.555 12.727 12.898 13.068 13.236 13.404 13.571 13.736 13.901

Ar P


N2

= 204.8 kPa, 29.7 psia 20.979 16.655 21.625 17.129 22.264 17.597 22.894 18.058 23.517 18.513 24.133 18.962 24.742 19.404 25.344 19.842 25.939 20.273 26.527 20.7 27.109 21.121 27.685 21.538 28.255 21.949 28.819 22.357 29.378 22.759 29.931 23.157 30.479 23.552 31.021 23.942 31.558 24.328 32.09 24.71 32.618 25.089 33.14 25.464 33.658 25.835 34.172 26.203 34.681 26.568 35.186 26.93 35.687 27.288 36.183 27.644 36.676 27.996 37.164 28.346 37.649 28.692

Air

Ar/CH4 (90/10)

Ar/CH4 (95/5)

17.277 17.775 18.266 18.75 19.228 19.699 20.165 20.624 21.078 21.526 21.969 22.407 22.84 23.268 23.691 24.11 24.524 24.934 25.34 25.742 26.14 26.534 26.924 27.311 27.695 28.075 28.451 28.825 29.195 29.562 29.927

20.013 20.625 21.229 21.826 22.415 22.998 23.573 24.142 24.705 25.261 25.811 26.355 26.893 27.426 27.953 28.474 28.991 29.502 30.008 30.51 31.006 31.499 31.986 32.47 32.949 33.424 33.894 34.361 34.824 35.284 35.739

20.505 21.134 21.755 22.369 22.975 23.574 24.166 24.751 25.329 25.901 26.467 27.027 27.581 28.129 28.671 29.209 29.74 30.267 30.788 31.305 31.817 32.324 32.826 33.325 33.818 34.308 34.793 35.275 35.752 36.226 36.696


Carrier Gas Viscosity (continued) T, °C

He

H2

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300

18.704 19.167 19.625 20.08 20.531 20.978 21.421 21.861 22.297 22.73 23.159 23.586 24.009 24.43 24.847 25.262 25.675 26.084 26.491 26.896 27.298 27.698 28.096 28.492 28.885 29.276 29.666 30.053 30.438 30.822 31.203

8.4024 8.6114 8.8179 9.0222 9.2241 9.4239 9.6217 9.8174 10.011 10.203 10.393 10.582 10.769 10.954 11.137 11.319 11.5 11.68 11.857 12.034 12.21 12.384 12.557 12.729 12.899 13.069 13.238 13.405 13.572 13.738 13.903


Ar

N2

P = 308.2 kPa, 44.7 psia 21.001 16.672 21.647 17.146 22.285 17.613 22.915 18.074 23.537 18.528 24.152 18.977 24.76 19.419 25.361 19.856 25.956 20.287 26.544 20.713 27.126 21.134 27.701 21.55 28.271 21.962 28.835 22.369 29.393 22.771 29.945 23.169 30.493 23.563 31.035 23.953 31.572 24.338 32.103 24.72 32.631 25.099 33.153 25.474 33.671 25.845 34.184 26.213 34.693 26.577 35.198 26.939 35.698 27.297 36.194 27.652 36.687 28.005 37.175 28.354 37.66 28.701

Air

17.296 17.794 18.284 18.767 19.244 19.715 20.18 20.639 21.092 21.54 21.982 22.42 22.852 23.28 23.703 24.121 24.535 24.945 25.351 25.752 26.15 26.544 26.934 27.321 27.704 28.084 28.46 28.834 29.204 29.571 29.935

Ar/CH4 (90/10)

20.033 20.644 21.248 21.844 22.433 23.015 23.59 24.158 24.72 25.276 25.825 26.369 26.907 27.439 27.966 28.487 29.003 29.514 30.02 30.521 31.018 31.51 31.997 32.48 32.959 33.434 33.904 34.371 34.834 35.293 35.749

Ar/CH4 (95/5)

20.527 21.155 21.775 22.388 22.993 23.592 24.183 24.768 25.346 25.917 26.483 27.042 27.596 28.143 28.685 29.222 29.754 30.28 30.801 31.317 31.829 32.336 32.838 33.336 33.829 34.319 34.804 35.285 35.763 36.236 36.706


Carrier Gas Viscosity (continued)

T, °C

He

H2

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300

18.71 19.172 19.63 20.085 20.535 20.982 21.425 21.865 22.301 22.734 23.163 23.59 24.013 24.433 24.851 25.266 25.678 26.088 26.495 26.899 27.302 27.701 28.099 28.495 28.888 29.279 29.668 30.056 30.441 30.824 31.206

8.406 8.6149 8.8213 9.0254 9.2273 9.427 9.6246 9.8203 10.014 10.206 10.396 10.584 10.771 10.956 11.14 11.322 11.502 11.682 11.86 12.036 12.212 12.386 12.559 12.731 12.901 13.071 13.24 13.407 13.574 13.74 13.904

Ar P


N2

= 446.1 kPa, 64.7 psia 21.032 16.696 21.676 17.169 22.313 17.636 22.942 18.096 23.563 18.549 24.178 18.997 24.785 19.439 25.385 19.875 25.979 20.306 26.567 20.731 27.148 21.152 27.723 21.567 28.292 21.978 28.855 22.385 29.413 22.786 29.965 23.184 30.512 23.578 31.053 23.967 31.59 24.353 32.121 24.734 32.648 25.113 33.17 25.487 33.687 25.858 34.2 26.226 34.709 26.59 35.213 26.951 35.713 27.309 36.209 27.664 36.702 28.016 37.19 28.366 37.674 28.712

Air

Ar/CH4 (90/10)

Ar/CH4 (95/5)

17.322 17.818 18.307 18.79 19.266 19.736 20.2 20.658 21.111 21.558 22 22.437 22.869 23.296 23.719 24.137 24.55 24.96 25.365 25.766 26.164 26.557 26.947 27.334 27.717 28.096 28.472 28.845 29.215 29.582 29.946

20.061 20.671 21.274 21.869 22.457 23.038 23.612 24.18 24.741 25.296 25.845 26.388 26.925 27.457 27.983 28.504 29.02 29.53 30.036 30.537 31.033 31.524 32.012 32.494 32.973 33.447 33.918 34.384 34.847 35.306 35.761

20.556 21.183 21.802 22.414 23.019 23.616 24.207 24.79 25.368 25.939 26.504 27.062 27.615 28.163 28.704 29.24 29.771 30.297 30.818 31.334 31.845 32.352 32.854 33.351 33.844 34.333 34.818 35.299 35.776 36.25 36.719


35

Ar Ar/CH4

30

He

Viscosity [µPa*s]

Air N2

25

20

15

H2

10 0

Figure 1.1

50

100

150 200 Temperature [°C]

250

300

Viscosity vs. temperature at 29.7 psia.

35

Ar Ar/CH4 He

30

Viscosity [µPa*s]

Air 25

N2

20

15 H2 10 0.0020

0.0025

0.0030

Temperature [1/Kelvin] Figure 1.2



0.0035


35

Ar Ar/CH4 He

30

Viscosity [µPa*s]

Air N2

25

20

15 H2 10 0

Figure 1.3

50

100

150 200 Temperature [°C]

250

300


35

Ar Ar/CH4 He

30

Viscosity [µPa*s]

Air 25

N2

20

15 H2 10 0.0020

0.0025

0.0030

Temperature [1/Kelvin] Figure 1.4



0.0035


GAS CHROMATOGRAPHIC SUPPORT MATERIALS FOR PACKED COLUMNS The following table lists the more common solid supports used in packed column gas chromatography and preparative scale gas chromatography, along with relevant properties.1–4 The performance of several of these materials can be improved significantly by acid washing and treatment with DMCS (dimethyldichlorosilane) to further deactivate the surface. The nonacid-washed materials can be treated with hexamethyldisilane to deactivate the surface; however, the deactivation is not as great as that obtained by an acid wash followed by DMCS treatment. Most of the materials are available in several particle size ranges. The use of standard sieves will help insure reproducible size packings from one column to the next. Data are provided for the Chromosorb family of supports since they are among the most well characterized. It should be noted that other supports are available to the chromatographer, with a similar range of properties provided by the Chromosorb series.

REFERENCES 1. Poole, C.F. and Schuette, S.A., Contemporary Practice of Chromatography, Elsevier, Amsterdam, 1984. 2. Gordon, A.J. and Ford, R.A., The Chemist’s Companion, John Wiley & Sons, New York, 1972. 3. Heftmann, E., Ed., Chromatography: A Laboratory Handbook of Chromatographic and Electrophoretic Methods, 3rd ed., Van Nostrand Reinhold, New York, 1975. 4. Grant, D.W., Gas–Liquid Chromatography, Van Nostrand Reinhold, London, 1971.


Support Type

Support Name

Density (Free Fall), g/ml

Density (Packed), g/ml

pH

Surface Area, m2/g

Maximum Liquid Loading

Color

Chromosorb A

Diatomite

0.40

0.48

7.1

2.7

25%

Pink

Chromosorb G

Diatomite

0.47

0.58

8.5

0.5

5%

Chromosorb P

Diatomite firebrick

0.38

0.47

6.5

4.0

30%

Oyster white Pink

Chromosorb W

Diatomite

0.18

0.24

8.5

1.0

15%

White

Chromosorb 750

Diatomite

0.33

0.49

0.75

7%

White

Chromosorb R-4670-1

Diatomite

5–6

Low

White

Chromosorb Ta

Polytetrafluoroethylene

7.5

5%

White

Kel-Fa

Chlorofluorocarbon

2.2

20%

White


0.42

0.49

Notes Most useful for preparative gas chromatography; high strength; high liquid phase capacity; low surface activity High mechanical strength; low surface activity; high density High mechanical strength; high liquid capacity; moderate surface activity; for separations of moderately polar compounds Lower mechanical strength than pink supports; very low surface activity; for polar compound separation Highly inert surface; useful for biomedical and pesticide analysis; mechanical strength similar to Chromosorb G Ultrafine particle size used to coat inside walls of capillary columns; typical particle size is 1–4 µm Maximum temperature of 240°C; handling is difficult due to static charge; tends to deform when compressed; useful for analysis of high-polarity compounds Hard, granular chlorofluorocarbon; mechanically similar to Chromosorbs; generally gives poor efficiency; use below 160°C, very rarely used


Gas Chromatographic Support Materials for Packed Columns

Support Type

Support Name Fluoropak-80

a

Fluorocarbon resin

Teflon-6a

Polytetrafluoroethylene

T-Port-Fa Porasil (Types A through F)

Polytetrafluoroethylene Silica

a

Density (Free Fall), g/ml

Density (Packed), g/ml

pH

Surface Area, m2/g 1.3

Maximum Liquid Loading 5%

Color

Notes

White

Granular fluorocarbon with sponge-like structure; low liquid phase capacity; use below 275°C Usually 40–60 (U.S.) mesh size; for relatively nonpolar liquid phases; low mechanical strength; high inert surface; difficult to handle due to static charge; difficult to obtain good coating of polar phases due to highly inert surface Use below 150°C Rigid, porous silica bead; controlled pore size varies from 10–150 mm; highly inert; also used as a solid adsorbent

10.5

20%

White

2–500, type dependent

40%

White White

0.5

The fluorocarbon supports can be difficult to handle since they develop an electrostatic charge easily. It is generally advisable to work with them below 19°C (solid transition point), using polyethylene laboratory ware.



Gas Chromatographic Support Materials for Packed Columns (continued)


MESH SIZES AND PARTICLE DIAMETERS The following tables give the relationship between particle size diameter (in µm) and several standard sieve sizes. The standards are as follows: United States Standard Sieve Series, ASTM E-11-01 Canadian Standard Sieve Series, 8-GP-16 British Standards Institution, London, BS-410-62 Japanese Standard Specification, JI S-Z-8801 French Standard, AFNOR X-11-501 German Standard, DIN-4188 Mesh Sizes and Particle Diameters Particle Size, µm

U.S. Sieve Size

4000 2000 1680 1420 1190 1000 841 707 595 500 420 354 297 250 210 177 149 125 105 88 74 63 53 44 37

5 10 12 14 16 18 20 25 30 35 40 45 50 60 70 80 100 120 140 170 200 230 270 325 400


Tyler Mesh Size — 9 10 12 14 16 20 24 28 32 35 42 48 60 65 80 100 115 150 170 200 250 — — —

British Sieve Size — 8 — — — — 18 — 25 — 36 — 52 60 72 85 100 120 150 170 200 240 300 350 —

Japanese Sieve Size

Canadian Sieve Size

— 9.2 — — — — 20 — 28 — 36 — 52 55 65 80 100 120 145 170 200 250 280 325 —

— 8 — — — — 18 — 25 — 36 — 52 60 72 85 100 120 150 170 200 240 300 350 —


French and German Sieve Sizes Particle Size, µm

Sieve Size

2000 800 500 400 315 250 200 160 125 100 80 63 50 40

34 30 28 27 26 25 24 23 22 21 20 19 18 17

Mesh Size Relationships Mesh Range

Top Screen Opening, µm

Bottom Screen Opening, µm

Micron Screen, µm

Range Ratio

10/20 10/30 20/30 30/40 35/80 45/60 60/70 60/80 60/100 70/80 80/100 100/120 100/140 120/140 140/170 170/200 200/230 230/270 270/325 325/400

2000 2000 841 595 500 354 250 250 250 210 177 149 149 125 105 88 74 63 53 44

841 595 595 420 177 250 210 177 149 177 149 125 105 105 88 74 63 53 44 37

1159 1405 246 175 323 104 40 73 101 33 28 24 44 20 17 14 11 10 9 7

2.38 3.36 1.41 1.41 2.82 1.41 1.19 1.41 1.68 1.19 1.19 1.19 1.42 1.19 1.19 1.19 1.17 1.19 1.20 1.19



PACKED COLUMN SUPPORT MODIFIERS During the analysis of strongly acidic or basic compounds, peak tailing is almost always a problem, especially when using packed columns. Pretreatment of support materials, such as acid washing and treatment with DMCS (dimethyldichlorosilane), will usually result in only modest improvement in performance. A number of modifiers can be added to the stationary phase (in small amounts, 1 to 3%) in certain situations to achieve a reduction in peak tailing. The following table provides several such reagents.1 It must be remembered that the principal liquid phase must be compatible with any modifier being considered. Thus, the use of potassium hydroxide with polyester or polysiloxane phases would be inadvisable, since this reagent can catalyze the depolymerization of the stationary phase. It should also be noted that the use of a tail-reducing modifier may lower the maximum working temperature of a particular stationary phase.

REFERENCES 1. Poole, C.F. and Schuette, S.A., Contemporary Practice of Chromatography, Elsevier, Amsterdam, 1984.

Packed Column Support Modifiers Compound Class

Modifier Reagents

Acids

Phosphoric acid, FFAP (carbowax-20m-terephthalic acid ester), trimer acid

Bases

Potassium hydroxide, polyethyleneimine, polypropyleneimine, N,N′-bis-L-methylheptyl-pphenylenediamine, sodium metanilate, THEED (tetrahydroxyethylenediamine)


Notes These modifiers will act as subtractive agents for basic components in the sample; FFAP will selectively abstract aldehydes; phosphoric acid may convert amides to the nitrile (of the same carbon number), desulfonate sulfur compounds, and may esterify or dehydrate alcohols These modifiers will act as subtractive agents for acidic components in the sample; polypropyleneimine will selectively abstract aldehydes, polyethyleneimine will abstract ketones


PROPERTIES OF CHROMATOGRAPHIC COLUMN MATERIALS The following table provides physical, mechanical, electrical, and (where appropriate) optical properties of materials commonly used as chromatographic column tubing.1–6 The data will aid the user in choosing the appropriate tubing material for a given application. The mechanical properties are measured at ambient temperature unless otherwise specified. The chemical incompatibilities cited are usually only important when dealing with high concentrations, which are normally not encountered in gas chromatography. Caution is urged nevertheless.

REFERENCES 1. 2. 3. 4. 5. 6.

Materials Engineering: Materials Selector, Penton/IPC, Cleveland, 1986. Khol, R., Ed., Machine Design, Materials Reference Issue, 58, 1986. Polar, J.P., A Guide to Corrosion Resistance, Climax Molybdenum Co., Greenwich, CT, 1981. Fontana, M.G. and Green, N.D., Corrosion Engineering, McGraw-Hill Book Co., New York, 1967. Shand, E.B., Glass Engineering Handbook, McGraw-Hill Book Co., New York, 1958. Fuller, A., Corning Glass Works, Science Products Division, Corning, NY, 1988 (private communication). Properties of Chromatographic Column Materials Aluminum (Alloy 3003) Density Hardness (Brinell) Melting range Coefficient of expansion (20–300°C) Thermal conductivity (20°C, annealed) Specific heat (100°C) Tensile strength (hard) Tensile strength (annealed)

2.74 g/ml 28–55 643.3–654.4°C 2.32 × 10–5 °C–1 193.14 W/(m·K) 921.1 J/(kg·K) 152 MPa 110 MPa

Note: Soft and easily formed into coils; high thermal conduction; incompatible with strong bases, nitrates, nitrites, carbon disulfide, and diborane. Actual alloy composition: Mn = 1.5%; Cu = 0.05–0.20%; balance is Al.

Copper (Alloy C12200)a Density Hardness (Rockwell-f) Melting point Coefficient of expansion (20–300°C) Thermal conductivity (20°C) Specific heat (20°C) Tensile strength (hard) Tensile strength (annealed) Elongation (in 0.0508 m, annealed) % Note:

a

8.94 g/ml 40–45 1082.8°C 1.76 × 10–5 °C–1 339.22 W/(m·K) 385.11 J/(kg·K) 379 MPa 228 MPa 45

Copper columns often cause adsorption problems; incompatible with amines, anilines, acetylenes, terpenes, steroids, and strong bases. High-purity phosphorus deoxidized copper.



Properties of Chromatographic Column Materials (continued) Borosilicate Glass Density Hardness (Moh 100) Young’s modulus (25°C) Poisson’s ratio (25°C) Softening point Annealing point Melting point Strain point Coefficient of expansion (average) Thermal conductivity Specific heat Refractive indexa Normal service temperature (annealed) Extreme service temperature (annealed) Critical surface tension

2.24 g/ml 418 62 GPA 0.20 806.9°C 565°C 1600°C 520°C 3 × 10–6 °C–1 1.26 W/(m·K) 710 J/(kg·K) 1.473 215°C 476°C 750 mN/m

Note:

a

Has been used for both packed columns and capillary columns; incompatible with fluorine, oxygen difluoride, and chlorine trifluoride. Clear grade, at 588 mm.

Fused Silica (SiO2) Density Hardness (Moh) Young’s modulus (25°C) Poisson’s ratio (25°C) Softening point Annealing point Melting point Strain point Coefficient of expansion (average) Thermal conductivity Specific heat Refractive index (588 nm) Normal service temperature (annealed) Extreme service temperature (annealed) Critical surface tension Note:

Used for capillary columns; typical inside diameters range from 5 to 530 µm; coated on outside surface by polyimide or aluminum to prevent surface damage; incompatible with fluorine, oxygen difluoride, chlorine trifluoride, and hydrogen fluoride.

Nickel (Monel R-405) Density Hardness (Brinell, 21°C) Melting range Coefficient of expansion (21–537°C) Thermal conductivity (21°C) Specific heat (21°C) Tensile strength (hard) Tensile strength (annealed) Elongation (in 2 in., 21.1°C) Note:


2.15 g/ml 6 72 GPa 0.14 1590°C 1105°C 1704°C 1000°C 5 × 10–7 °C–1 1.5 W/(m·K) 1000 J/(kg·K) 1.458 886°C 1086°C 760 mN/m

8.83 g/ml 110–245 1298.89–1348.89°C 1.64 × 10–5 °C–1 21.81 W/(m·K) 427.05 J/(kg·K) 483 MPa 793 MPa 15–50%

Provides excellent corrosion resistance; no major chemical incompatibilities. Actual alloy composition: Ni = 66%; Cu = 31.5%; Fe = 1.35%, C = 0.12%; Mn = 0.9%; S = 0.005%; Si = 0.15%.


Properties of Chromatographic Column Materials (continued) Polytetrafluoroethylene (Teflon) Specific gravity Hardness (Rockwell-d) Melting range Coefficient of expansion Thermal conductivity (21°C) Specific heat (21°C) Tensile strength Refractive indexa

2.13–2.24 52–65 1298.89–1348.89°C 1.43 × 10–4 °C–1 2.91 W/m·K 1046.7 J/kg·K 17–45 MPa 1.35

Note:

a

Flexible and easy to use; cannot be used above 230°C; thermal decomposition products are toxic; tends to adsorb many compounds, which may increase tailing. No major chemical incompatibilities. Using sodium-D line, as per ASTM standard test D542-50.

Stainless Steel (304) Density Hardness (Rockwell B) Melting range Coefficient of expansion (0–100°C) Thermal conductivity (0°C) Specific heat (0–100°C) Tensile strength (hard) Tensile strength (annealed) Elongation (in 2 in.)

7.71 g/ml 149 1398.9–1421.1°C 1.73 × 10–5 °C–1 16.27 W/(m·K) 502.42 J/(kg·K) 758 MPa 586 MPa 60%

Note:

Good corrosion resistance; easily brazed using silver bearing alloys; high nickel content may catalyze some reactions at elevated temperatures. No major chemical incompatibilities. Actual alloy composition: C = 0.08%; Mn = 2% (max); Si = 1% (max); P = 0.045% (max); S = 0.030 (max); Cr = 18–20%; Ni = 8–12%, balance is Fe. The low-carbon alloy, 304L, is similar except for C = 0.03% max and is more suitable for applications involving welding operations, and where high concentrations of hydrogen are used.

Stainless Steel (316) Density Hardness (Rockwell B) Melting range Coefficient of expansion (0–100°C) Thermal conductivity (0°C) Specific heat (0–100°C) Tensile strength (annealed) Elongation (in 2 in.) Note:


7.71 g/ml 149 1371.1–1398.9°C 7.17 × 10–5 °C–1 16.27 W/(m·K) 502.42 J/(kg·K) 552 MPa 60%

Best corrosion resistance of any standard stainless steel, including the 304 varieties, especially in reducing and high-temperature environments. Actual alloy composition: C = 0.08% (max), Mn = 2% (max); Si = 1% (max); P = 0.045% (max); S = 0.030 (max); Cr = 16–18%; Ni = 10–14%, Mo = 2–3%, balance is Fe. The low-carbon alloy, 316L, is similar except for C = 0.03% max and is more suitable for applications involving welding operations, and where high concentrations of hydrogen are used.


PROPERTIES OF SOME LIQUID PHASES FOR PACKED COLUMNS The following table lists some of the more common gas–chromatographic liquid phases that have been used historically, along with some relevant data and notes.1–3 Many of these phases have been superseded by silicone phases used in capillary columns, but the liquid phases still find applications in many instances. This is especially true with work involving established protocols, such as ASTM or AOAC methods. Moreover, the data are still useful in interpreting analytical results in the literature. The minimum temperatures, where reported, indicate the point at which some of the phases approach solidification, or when the viscosity increases to the extent that performance is adversely affected. The maximum working temperatures are determined by vapor pressure (liquid phase bleeding) and chemical stability considerations. The liquid phases are listed by their most commonly used names. Where appropriate, chemical names or common generic names are provided in the notes. The McReynolds constants (a modification of the Rohrschneider constant) tabulated here are based on the retention characteristics of the following test probe samples: Constant

Test Probe

X Y Z U S

Benzene 1-Butanol 3-Pentanone 1-Nitropropane Pyridine

Compounds that are chemically similar to these probe solutes will show similar retention characteristics. Thus, benzene can be thought of as representing lower aromatic or olefinic compounds. Higher values of the McReynolds constant usually indicate a longer retention time (higher retention volume) for a compound represented by that constant, for a given liquid (stationary) phase. Solvents:

Ace—acetone Chlor—chloroform Pent—n-pentane DMP—dimethylpentane EAC—ethyl acetate

Polarity:

N—nonpolar P—polar I—intermediate polarity HB—hydrogen bonding S—specific interaction

MeCl—methylene chloride Tol—toluene MeOH—methanol H2O—water

REFERENCES 1. McReynolds, W.O., Characterization of some liquid-phases, J. Chromatogr. Sci., 8, 685, 1970. 2. McNair, H.M. and Bonelli, E.J., Basic Gas Chromatography, Varian Aerograph, Palo Alto, 1968. 3. Heftmann, E., Chromatography: A Laboratory Handbook of Chromatographic and Electrophoretic Methods, 3rd. ed., Van Nostrand Reinhold, New York, 1975.


Tmin, °C

Tmax, °C

–4

25

I

Ace

25 5 59

180 50 75

I I I

0

180

P

Ace Chlor MeCl Chlor MeCl, MeOH Chlor MeCl

80

P

MeOH

275 300 300 275 300 300+ 275 280

N N N N N N N N

Chlor Chlor Chlor Chlor Chlor Chlor Chlor Tol

Armeen SD Armeen 12D Armeen Armeen 2HT Arneel DD Arochlor 1242

100 100 125 100 100 125

P, P, P, P, P

Asphalt

300

N

Chlor MeCl

I I

Chlor Chlor Tol Chlor Tol

Liquid Phase Acetonyl acetone (2,5-hexanedione) Acetyl tributyl citrate Adiponitrile Alka terge-T, amine surfactant Amine 220 Ansul ether Apiezon H Apiezon J Apiezon L Apiezon M Apiezon N Apiezon K Apiezon W Apolane-87

Atpet 80 p,p-Azoxydiphenetol Baymal Beeswax Bentone-34


50 50 50 50 50 50 50 30

130

20

140 300 200 200

Polarity

S, HB HB HB HB

S

Solvents

X

McReynolds Constant Y Z U S

Notes

s

MeCl MeCl MeCl MeCl

135

268

202

314

233 1,4-Dicyanobutane 60% oxazoline; weakly cationic

117

380

181

293

133

59 38 32 31 38

56 36 22 22 40

81 27 15 15 28

151 49 32 30 52

129 57 42 40 58

82 21

135 10

99 3

155 12

154 35

Chlor MeCl Chlor MeCl Tol Chlor MeOH Ace

2-(8-heptadecenyl)-2-imidazolineethanol Tetraethylene glycol dimethyl ether; used for hydrocarbons Low-vapor-pressure hydrocarbon oil Low-vapor-pressure hydrocarbon oil Low-vapor-pressure hydrocarbon oil Low-vapor-pressure hydrocarbon oil Low-vapor-pressure hydrocarbon oil Low-vapor-pressure hydrocarbon oil Low-vapor-pressure hydrocarbon oil 24,24-diethyl-19,29-dioctadecyl heptatetracontane; C-87 hydrocarbon Primary aliphatic amine Secondary aliphatic amine Aliphatic nitrile Chlorinated polyphenyl; used for gases; may be carcinogenic Complex mixture of aliphatic, aromatic, and heterocyclic compounds Sorbitan partial fatty acid esters

43

110

61

88

122

Colloidal alumina For essential oils Dimethyl dioctadecylammonium bentonite


Properties of Some Liquid Phases for Packed Columns

150

I

Chlor

Benzylamine adipate Benzyl cellosolve

125 50

I

Chlor Ace

Benzyl cyanide Benzyl cyanideAgNO3 Benzyl diphenyl Benzyl ether Bis(2-butoxyethyl) phthalate Bis(2-ethoxyethyl) phthalate Bis(2-ethoxyethyl) sebacate N,N-Bis(2-cyanoethyl formamide) Bis(2-ethoxyethyl) adipate Bis(2-methoxyethyl) adipate Bis(2-ethylhexyl) tetrachlorophthalate Butanediol adipate Butanediol 1,4succinate

50 25

I S

MeOH MeCl

100 50 175

I I I

Ace Chlor MeCl MeOH

2-(Benzyloxy ethanol); for hydrocarbons Phenyl acetonitrile

Dibenzyl ether 151

282

227

338

267

214

375

305

446

364

151

306

211

320

274

690

991

853

110

000

0

125

I

MeOH

0

150

I

Ace

20

150

I

Ace Chlor

0

150

I

Chlor MeCl

112

150

123

108

181

60

225 225

I, P I, P

Chlor MeCl Chlor

370

571

488

651

611

50

I

Chlor

100

P

Ace

Bis[2-(2-methoxyethoxy) ethyl] ether Carbitol Carbowax 300

10

100

P

MeCl

Carbowax 400

10

125

P

MeCl

Carbowax 400 monooleate

10

125

P

MeCl


For hydrocarbons, aromatics, heterocycles, sulfur compounds

333

653

405

(BDS) craig polyester; for alcohols, aromatics, heterocycles, fatty acids and esters, hydrocarbons Tetraethylene glycol dimethylether Glycol ether (molecular mass 134); for aldehydes, ketones Polyethylene glycol; average molecular mass 50,000

20

Ace

1 × 104

100,000

Tol

4 × 104

>50,000

Solvent

OV-17, phenylmethyl silicone

4

McReynolds Constants 5 6 7

1

2

3

8

9

I

119

158

162

243

202

112

119

105

184

69

50% methyl, similar phase: SP-2250

350

I

160

188

191

283

253

133

152

132

228

99

65% phenyl

20

350

I

178

204

208

305

280

144

169

147

215

113

75% phenyl

20

350

I

101

143

142

213

174

99

—

—

33% phenyl

Polarity

10

Notes

CH3 Si

O

φ

n

OV-22, phenylmethyl-dimethyl silicone

CH3

φ

Si O

Si

φ

φ

n

O m

OV-25, phenylmethyl-dimethyl silicone

CH3

φ

Si

Si

O

φ

n

O

φ

m

OV-61, diphenyl-dimethyl silicone

φ Si φ

CH3 Si

O n

CH3

O m


—

86


Silicone Liquid Phases (continued)

φ

CH3

Si O

Si O

φ

CH3

n

Tol

CH3

CH3 Si O

(CH2)2

CH3

C

N

Gum

20

350

I

40

86

76

114

85

20

250

N, I

36

108

93

139

86

57

—

39

—

—

74

—

29

—

—

5.5% phenyl, similar phases: SE-52, SE54

m

OV-105, cyano propylmethyl-dimethyl silicone

Si O

8 × 105

Ace

1500

m

n

OV-202, trifluoropropyl-methyl silicone

Chlor

1 × 104

500

0

275

I, P

146

238

358

468

310

202

139

56

283

60

50% trifluoropropyl fluid, similar phase: SP-2401

Chlor

2 × 105

10,000

20

275

I, P

146

238

358

468

310

206

139

56

283

60

50% trifluoropropyl, similar phases: QF-1, FS-1265, SD-2401

CH3 Si

O

(CH2)2 CF 3

n

OV-210, trifluoropropyl-methyl silicone

CH3 Si

O

(CH2)2 CF 3

n



OV-73, diphenyl-dimethyl silicone gum

Liquid Phase

Solvent

Average Molecular Mass

OV-215, trifluoropropyl-methyl silicone gum

Viscosity

Tmin, °C

Tmax, °C

Gum

McReynolds Constants 4 5 6 7

Polarity

1

2

3

8

9

10

Notes

I, P

149

240

363

478

315

208

—

56

—

—

50% trifluoropropyl

25% phenyl, 25% cyanopropylmethyl; similar phases: EX60, AN-600

CH3 Si

O

(CH2)2 CF 3

n

OV-225, cyanopropylmethylphenyl methylsilicone

CH3

Si

(CH2)2

φ

C

8 × 103

9000

20

275

I, P

228

369

338

492

386

282

226

150

342

117

Ace

5 × 103

20,000

20

275

P

781

1006

885

1177

1089

—

—

—

—

—

Chlor

16,000– 20,000

Waxy solid

50

450

I

47

80

103

148

96

—

—

—

—

—

CH3

O

Si

Ace

O

N

n

OV-275, dicyanoallyl silicone Dexsil 300 copolymer

CH3

O

CH3

CH3

Si

CH3 CH 3

[B]

Si CH 3

φ

CH3 O

Si

O

CH3

[B] = CB10H10C, meta-carborane


Si CH3

O n

Carborane-methyl silicone; siloxane to carborane ratio, 4:1; used for methyl esters, aromatic amines, halogenated alcohols, pesticides, polyphenyl ethers, silicone oils


Silicone Liquid Phases (continued)

CH3

Si

Chlor

12,000–16,000

—

20

375

I

60

115

140

188

174

—

—

—

—

—

Carborane-methyl phenyl silicone copolymer; siloxane to carborane ratio, 5:1

20

375

I

85

165

170

240

180

—

—

—

—

—

Carborane-methylβ-silicone cyanoethyl copolymer; siloxane to carborane ratio, 5:1

CH3 CH 3

[B]

Si

CH 3

CH3 O

CH 3

Si

O

Si

O

CH3

CH3

n

[B] = CB10H10C meta-carborane Dexsil 410

CH3

Si

Chlor

CH3

O CH3

Si

C CH3

Si CH 3

N

CH2

CH 3 [B]

9000–12,000

CH3 O

Si CH3

[B] = CB10H10C


CH2 O

Si CH3

O n


Dexsil 400


MESOGENIC STATIONARY PHASES The following table lists the liquid crystalline materials that are useful as gas chromatographic stationary phases in both packed and open tubular column applications. In each case, the name, structure, and transition temperatures are provided (where available), along with a description of the separations that have been done using these materials. The table has been divided into two sections. The first section contains information on phases that have either smectic or nematic phases or both, while the second section contains mesogens that have a cholesteric phase. It should be noted that each material may be used for separations other than those listed, but the listing contains the applications reported in the literature. It should be noted that some of the mesogens listed in this table are not commercially available and must be prepared synthetically for laboratory use. The reader is referred to the appropriate citation for details.

REFERENCES 1. Panse, D.G., Naikwadi, K.P., Bapat, B.V., and Ghatge, B.B., Applications of laterally mono and disubstituted liquid crystals as stationary phases in gas liquid chromatography, Ind. J. Technol., 19, 518, 1981. 2. Grushka, E. and Solsky, J.F., p-Azoxyanisole liquid crystal as a stationary phase for capillary column gas chromatography, Anal. Chem., 45, 1836, 1973. 3. Witkiewicz, Z. and Stanislaw, P., Separation of close-boiling compounds on liquid-crystalline stationary phases, J. Chromatogr., 154, 60, 1978. 4. Naikwadi, K.P., Panse, D.G., Bapat, B.V., and Ghatge, B.B., I. Synthesis and application of stationary phases in gas–liquid chromatography, J. Chromatogr., 195, 309, 1980. 5. Dewar, M. and Schroeder, J.P., Liquid crystals as solvents. I. The use of nematic and smectic phases in gas–liquid chromatography, J. Am. Chem. Soc., 86, 5235, 1964. 6. Dewar, M., Schroeder, J.P., and Schroeder, D., Molecular order in the nematic mesophase of 4,4′-din-hexyloxyazoxybenzene and its mixture with 4,4′-dimethoxyazoxybenzene, J. Org. Chem., 32, 1692, 1967. 7. Naikwadi, K.P., Rokushika, S., and Hatano, H., New liquid crystalline stationary phases for gas chromatography of positional and geometrical isomers having similar volatilities, J. Chromatogr., 331, 69, 1985. 8. Richmond, A.B., Use of liquid crystals for the separation of position isomers of disubstituted benzenes, J. Chromatogr. Sci., 9, 571, 1971. 9. Witkiewicz, Z., Pietrzyk, M., and Dabrowski, R., Structure of liquid crystal molecules and properties of liquid-crystalline stationary phases in gas chromatography, J. Chromatogr., 177, 189, 1979. 10. Ciosek, M., Witkiewicz, Z., and Dabrowski, R., Direct gas: chromatographic determination of 2napthylamine in 1-napthylamine on liquid-crystalline stationary phases, Chemia Analityczna, 25, 567, 1980. 11. Jones, B.A., Bradshaw, J.S., Nishioka, M., and Lee, M.L., Synthesis of smectic liquid-crystalline polysiloxanes from biphenylcarboxylate esters and their use as stationary phases for high-resolution gas chromatography, J. Org. Chem., 49, 4947, 1984. 12. Porcaro, P.J. and Shubiak, P., Liquid crystals as substrates in the GLC of aroma chemicals, J. Chromatogr. Sci., 9, 689, 1971. 13. Witkiewicz, Z., Suprynowicz, Z., Wojcik, J., and Dabrowski, R., Separation of the isomers of some disubstituted benzenes on liquid crystalline stationary phases in small-bore packed micro-columns, J. Chromatogr., 152, 323, 1978. 14. Dewar, M. and Schroeder, J.P., Liquid-crystals as solvents. II. Further studies of liquid crystals as stationary phases in gas–liquid chromatography, J. Org. Chem., 30, 3485, 1965. 15. Witkiewicz, Z., Szule, J., Dabrowski, R., and Sadowski, J., Properties of liquid crystalline cyanoazoxybenzene alkyl carbonates as stationary phases in gas chromatography, J. Chromatogr., 200, 65, 1980.



16. Witkiewicz, Z., Suprynowicz, Z., and Dabrowski, R., Liquid crystalline cyanoazoxybenzene alkyl carbonates as stationary phases in small-bore packed micro-columns, J. Chromatogr., 175, 37, 1979. 17. Lochmüller, C.H. and Souter, R.W., Direct gas chromatographic resolution of enantiomers on optically active mesophases, J. Chromatogr., 88, 41, 1974. 18. Markides, K.E., Nishioka, M., Tarbet, B.J., Bradshaw, J.S., and Lee, M.L., Smectic biphenylcarboxylate ester liquid crystalline polysiloxane stationary phase for capillary gas chromatography, Anal. Chem., 57, 1296, 1985. 19. Vetrova, Z.P., Karabanov, N.T., Shuvalova, T.N., Ivanova, L.A., and Yashin, Y.I., The use of p-n-butyl oxybenzoic acid as liquid crystalline sorbent in gas chromatography, Chromatographia, 20, 41, 1985. 20. Cook, L.E. and Spangelo, R.C., Separation of monosubstituted phenol isomers using liquid crystals, Anal. Chem., 46, 122, 1974. 21. Kong, R.C. and Milton, L.L., Mesogenic polysiloxane stationary phase for high resolution gas chromatography of isomeric polycyclic aromatic compounds, Anal. Chem., 54, 1802, 1982. 22. Bartle, K.D., El-Nasri, A.I., and Frere, B., Identification and Analysis of Organic Pollutants in Air, Ann Arbor Science, Ann Arbor, MI, 1984, 183 pp. 23. Finklemann, H., Laub, R.J., Roberts, W.E., and Smith, C.A., Use of mixed phases for enhanced gas chromatographic separation of polycyclic aromatic hydrocarbons. II. Phase transition behavior, masstransfer non-equilibrium, and analytical properties of a mesogen polymer solvent with silicone diluents, in Polynuclear Aromatic Hydrocarbons, Phys. Biol. Chem. 6th Int. Symp., Cooke, M., Ed., Battelle Press, Columbus, OH, 1982, p. 275. 24. Janini, G.M., Recent usage of liquid crystal stationary phases in gas chromatography, Adv. Chromatogr., 17, 231, 1979. 25. Witkiewicz, Z. and Waclawczyk, A., Some properties of high-temperature liquid crystalline stationary phases, J. Chromatogr., 173, 43, 1979. 26. Zielinski, W.L., Johnston, R., and Muschik, G.M., Nematic liquid crystal for gas–liquid chromatographic separation of steroid epimers, Anal. Chem., 48, 907, 1976. 27. Smith, T.R. and Wozny, M.E., Gas chromatographic separation of underivatized steroids using BPhBT liquid crystal stationary phase, J. High Resolut. Chromatogr. Chromatogr. Commun., 3, 333, 1980. 28. Barrall, E.M., Porter, R.S., and Johnson, J.F., Gas chromatography using cholesteryl ester liquid phase, J. Chromatogr., 21, 392, 1966. 29. Heath, R.R. and Dolittle, R.E., Derivatives of cholesterol cinnamate: a comparison of the separations of geometrical isomers when used as gas chromatographic stationary phases, J. High Resolut. Chromatogr. Chromatogr. Commun., 6, 16, 1983. 30. Sonnet, P.E. and Heath, R.R., Aryl substituted diastereomeric alkenes: gas chromatographic behavior on a non-polar versus a liquid crystal phase, J. Chromatogr., 321, 127, 1985.



Mesogenic Stationary Phases Name: 2-Chloro-4′-n-butyl-4-(4-n-butoxybenzoyloxy) azobenzene Structure: A R1

N

B

N

O

C

OR2

O

R1 = n−C4H9 A = Cl B=H R2 = n−C4H9

Thermophysical Properties: Solid → nematic 87.2°C Nematic → isotropic 168°C Analytical Properties: Separation of close-boiling disubstituted benzenes Reference: 1 Name: p-Azoxyanisole (4,4′-dimethoxyazoxybenzene) Structure:

CH 3O

N

N

OCH 3

O Thermophysical Properties: Solid → nematic 118°C Nematic → isotropic 135°C

Note: Supercooling has been noted at 110°C by observing nematic-like properties; liquid crystalline behavior can sometimes persist to 102°C

Analytical Properties: Separation of xylenes; separation of lower-molecular-weight aromatic hydrocarbon isomers, especially at the lower area of the nematic region. Reference: 2 Name: 2-Chloro-4′-n-butyl-4-(4-n-butoxybenzoyloxy) azobenzene Structure: A R1

N

B

N

O

C

OR2

O

R1 = n−C4H9 A = CI B=H R2 = CH3

Thermophysical Properties: Solid → nematic 92.5°C Nematic → isotropic 176°C

Note: Supercooling has been noted at 110°C by observing nematic-like properties; liquid crystalline behavior can sometimes persist to 102°C Analytical Properties: Separation of close-boiling disubstituted benzenes Reference: 1 Name: 2-Chloro-4′-n-butyl-4-(4-n-butoxybenzoyloxy) azobenzene Structure: A R1

N

N

B O

C O


OR2

R1 = C2H5 A = CI B=H R2 = n−C4H9


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → nematic 117°C Nematic → isotropic 172°C

Note: Supercooling has been noted at 110°C by observing nematic-like properties; liquid crystalline behavior can sometimes persist to 102°C Analytical Properties: Separation of close-boiling disubstituted benzenes Reference: 1 Name: 2-Chloro-4′-n-butyl-4-(4-ethoxybenzoyloxy) azobenzene Structure: B

A N

R1

N

O

OR2

C O

R1 = n−C4H9 A = Cl B=H R2 = C2H5

Thermophysical Properties: Solid → nematic 89.7°C Nematic → isotropic 170°C Analytical Properties: Separation of close-boiling disubstituted benzenes Reference: 1 Name: 2-Chloro-4′-methyl-4(4-butoxybenzoyloxy) azobenzene Structure: B

A N

R1

N

O

OR 2

C O

R1 = CH3 A = Cl B=H R2 = n−C4H9

Thermophysical Properties: Solid → nematic 112°C Nematic → isotropic 165°C Analytical Properties: Separation of close-boiling disubstituted benzenes Reference: 1 Name: 2-Chloro-4′-n-methyl-4-(4-ethoxybenzoyloxy) azobenzene Structure: A N

R1

B

N

O

OR 2

C O

Thermophysical Properties: Solid → nematic 128.3°C Nematic → isotropic 185°C Analytical Properties: Separation of close-boiling disubstituted benzenes Reference: 1 Name: p-Cyano-p′-pentoxyazoxybenzene Structure: NC

N O


N

O

n

C5H11

R1 = CH3 A = Cl B=H R2 = C2H5


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → nematic 124°C Nematic → isotropic 153°C Analytical Properties: Complete separation of ethyltoluenes, chlorotoluenes, bromotoluenes, and dichlorobenzenes; also, ethylbenzene from xylenes and propylbenzene from ethyltoluenes Reference: 3 Name: p-Cyano-p′-pentoxyazobenzene Structure: NC

N

N

O

C5H11

Thermophysical Properties: Solid → nematic 106°C Nematic → isotropic 116°C Analytical Properties: Separation of ethyltoluenes, chlorotoluenes, bromotoluenes, and dichlorobenzenes; also, ethylbenzenes from xylenes and propylbenzenes from ethylbenzenes Reference: 3 Name: p-Cyano-p′-pentoxyazoxybenzene (mixed isomers) Structure: NC

N

N

O

O

O

C5H11

Thermophysical Properties: Solid → nematic 93.5°C Nematic → isotropic 146.5°C Analytical Properties: Complete separation of ethyltoluenes, chlorotoluenes, bromotoluenes, and dichlorobenzenes; also, ethylbenzene from xylenes and propylbenzene from ethyltoluenes Reference: 3 Name: p-Cyano-p′-octoxyazoxybenzene (mixed isomers) Structure: NC

N

N

O

O

O

C8H17

Thermophysical Properties: Solid → smectic 71°C Smectic → nematic 117°C Nematic → isotropic 135°C Analytical Properties: Separation of ethyltoluenes, chlorotoluenes, bromotoluenes, and dichlorobenzenes; also, ethylbenzene from xylenes and propylbenzene from ethylbenzenes Reference: 3 Name: p-Cyano-p′-octoxyazoxybenzene Structure: NC

N O


N

O

C8H17


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → smectic 100.5°C Smectic → nematic 138.5°C Nematic → isotropic 148.5°C Analytical Properties: Separation of ethyltoluenes, chlorotoluenes, bromotoluenes, and dichlorobenzenes; also, ethylbenzene from xylenes and propylbenzene from ethylbenzenes Reference: 3 Name: 4′-n-Butyl-4(4-n-butoxybenzoyloxy) azobenzene Structure: O C4H9

N

N

O

C

O

n

C4H9

Thermophysical Properties: Solid → nematic 94°C Nematic → isotropic 234.5°C Analytical Properties: Separation of chlorinated biphenyls Reference: 4 Name: 4-4′-Di-n-heptyloxyazoxybenzene Structure: C7H15

O

N

N

O

C7H15

O Thermophysical Properties: Solid → nematic 95°C Nematic → isotropic 127°C Analytical Properties: Separation of meta- and para-xylene in nematic region Reference: 5 Name: 4,4′-Di-n-hexyloxyazoxybenzene Structure: n−C6H13

O

N

N

O

n−C6H13

O Thermophysical Properties: Solid → nematic 81°C Nematic → isotropic 129°C Analytical Properties: Separation of meta- and para-xylene using gas chromatography Reference: 5, 6 Name: 4′-Methoxy-4-(4-n-butoxybenzoyloxy) azobenzene Structure: O CH3O


N

N

O

C

O

C4H9


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → nematic 116°C Nematic → isotropic 280°C Analytical Properties: Separation of chlorinated biphenyls Reference: 4 Name: 2-Methyl-4′-n-butyl-4-(4-n-butoxybenzoyloxy) azobenzene Structure: B

A N

R1

N

O

OR2

C O

R1 = n−C4H9 A = CH3 B=H R2 = n−C4H9

Thermophysical Properties: Solid → nematic 90°C Nematic → isotropic 175°C Analytical Properties: Separation of close-boiling disubstituted benzenes Reference: 1 Name: 2-Methyl-4′-n-butyl-4-(p-methoxycinnamoyloxy) azobenzene Structure: CH3 N

n−C4H9

O

N

O

C

CH

OCH3

CH

Thermophysical Properties: Solid → nematic 109°C Nematic → isotropic 253°C Analytical Properties: Separation of positional isomers of aromatic hydrocarbons Reference: 7 Name: 2-Methyl-4′-methoxy-4-(4-ethoxybenzoyloxy) azobenzene Structure: CH3 CH3O

N

N

O O

C

C2H5

Thermophysical Properties: Solid → nematic 125°C Nematic → isotropic 244°C Analytical Properties: Separation of chlorinated biphenyls Reference: 4 Name: 2-Methyl-4′-methoxy-4-(4-methoxybenzoyloxy) azobenzene Structure: CH3 CH3O


N

N

O O

C

OCH3


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → nematic 160°C Nematic → isotropic 253°C Analytical Properties: Separation of chlorinated biphenyls Reference: 4 Name: 2-Methyl-4′-ethyl-4-(4′-methoxycinnamyloxy) azobenzene Structure: CH3 C2H5

N

O

N

O

C

CH

CH

OCH3

Thermophysical Properties: Solid → nematic 126°C Nematic → isotropic 262°C Analytical Properties: Separation of polyaromatic hydrocarbons and insect sex pheromones Reference: 5 Name: 2-Methyl-4′-methoxy-4-(p-methoxycinnamoyloxy) azobenzene Structure: CH3 O CH3

O

N

N

O

C

CH

CH

OCH3

Thermophysical Properties: Solid → nematic 149°C Nematic → isotropic 298°C Analytical Properties: Separation of positional isomers of aromatic compounds and geometrical isomers of sex pheromones Reference: 7 Name: 2-Methyl-4′-methyl-4-(4-ethoxybenzoyloxy) azobenzene Structure: CH3 CH3

N

O

N

O

C

O

Thermophysical Properties: Solid → nematic 125°C Nematic → isotropic 220°C Analytical Properties: Separation of chlorinated biphenyls Reference: 4 Name: 4,4′-Azoxyphenetole Structure: C2H5O

N

N O


OC2H5

C2H5


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → nematic 138°C Nematic → isotropic 168°C Analytical Properties: Separation of meta- and para-isomers of disubstituted benzenes Reference: 8 Name: 4,4-Biphenylylene-bis-[p-(heptoxy) benzoate] Structure: O

O C7H15O

CO

O

C

OC7H15

Thermophysical Properties: Solid → smectic 150°C Smectic → nematic 211°C Nematic → isotropic 316°C Analytical Properties: Separation of meta- and para-isomers of disubstituted benzenes Reference: 8 Name: p′-Ethylazoxybenzene p-cyanobenzoate (mixed isomers) Structure: C2H5

N

N

OC

O

O

O

CN

Thermophysical Properties: Melting range → 114–136°C Nematic → isotropic >306°C Analytical Properties: Separation of substituted xylenes Reference: 9 Name: p′-Ethylazoxybenzene p-cyanobenzoate (pure isomer) Structure:

C2H5

N

N O

OC

CN

O

Thermophysical Properties: Solid → nematic 115°C Nematic → isotropic 294°C Analytical Properties: Separation of nitronaphthalenes Reference: 10 Name: p′-Ethylazobenzene p-cyanobenzoate Structure:

C2H5

N

N

OC O

Thermophysical Properties: Solid → nematic 138–140°C Nematic → isotropic 292°C Analytical Properties: Separation of substituted xylenes Reference: 9


CN


Mesogenic Stationary Phases (continued) Name: p′-Ethylazobenzene p-methylbenzoate Structure:

N

C2H5

N

OC

CH3

O

Thermophysical Properties: Solid → nematic 108°C Nematic → isotropic 230°C Analytical Properties: Separation of nitronaphthalenes Reference: 10 Name: p-Ethylazoxybenzene p′-methylbenzoate (mixed isomers) Structure:

C2H5

N

N

OC

O

O

O

Thermophysical Properties: (directly after crystallization) Crystal → nematic 97.5°C Nematic → isotropic 250.5°C Analytical Properties: Separation of substituted Reference: 9

CH3

(after melting and cooling) Crystal → nematic 87.5–97.5°C Nematic → isotropic 250.5°C xylenes

Name: 4′-Methoxybiphenyl-4,4-[(allyloxy)phenyl] benzoate Structure:

CH2

CH(CH2)aO

a=1 b=2 c=2 R = OCH3

R

CO2 b

c

Thermophysical Properties: Solid → nematic 214°C Nematic → isotropic 290°C Analytical Properties: Suggested for separation of polycyclic aromatic compounds Reference: 11 Name: (S)-4-[(2-Methyl-1-butoxy)carbonyl]phenyl-4-[4-(4-pentenyloxy)phenyl] benzoate Structure:

CH2

CH(CH2)aO

R

CO2 b

c

a=3 b=2 c=1 R = COOCH2C*H(CH3)CH2CH3 Thermophysical Properties: Solid → smectic 105°C Smectic → isotropic 198°C Analytical Properties: Suggested for separation of polycyclic aromatic compounds Reference: 11



Mesogenic Stationary Phases (continued) Name: 4-Methoxyphenyl-4-[4-(allyloxy) phenyl] benzoate Structure:

CH2

CH(CH2)aO

R

CO2 b

c

a=1 b=2 c=1 R = OCH3 Thermophysical Properties: Solid → nematic 137°C Nematic → isotropic 243°C Analytical Properties: Suggested for the separation of polycyclic aromatic compounds Reference: 11 Name: 4-Methoxyphenyl-4-[4-(4-pentenyloxy) phenyl] benzoate Structure:

CH2

CH(CH2)aO

R

CO2 b

c

a=3 b=2 c=1 R = OCH3 Thermophysical Properties: Solid → smectic 133°C Smectic → nematic 172°C Nematic → isotropic 253°C Analytical Properties: Suggested for separation of polycyclic aromatic compounds Reference: 11 Name: p-Phenylene-bis-4-n-heptyloxybenzoate Structure: C7H15O

COO

OOC

OH15C7

Thermophysical Properties: Solid → smectic 83°C Smectic → nematic 125°C Nematic → isotropic 204°C Analytical Properties: Separation of 1- and 2-ethylnaphthalene; baseline separation of pyrazines Reference: 12 Name: 4-[(4-Dodecyloxyphenyl)azoxy]-benzonitrile Structure: NC

N O


N

O

C12H25


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → smectic 106°C Smectic → isotropic 147°C Analytical Properties: Marginal effectiveness in separating disubstituted benzene isomers Reference: 13 Name: 4-[(4-Pentyloxyphenyl)azoxy]-benzonitrile (mixed isomers) Structure: NC

N

N

O

O

O

C5H11

Thermophysical Properties: Solid → nematic 94°C Nematic → isotropic 141.5°C Analytical Properties: Does not separate diethylbenzene (DEB) isomers; good separation of disubstituted benzene isomers Reference: 13 Name: 4-[(4-Octyloxyphenyl)azoxy]-benzonitrile Structure: NC

N

N

O

C8H17

O Thermophysical Properties: Solid → smectic 101.5°C Smectic → nematic 137°C Nematic → isotropic 151.5°C Analytical Properties: Separates diethylbenzene isomers Reference: 13 Name: 4-[(4-Pentyloxyphenyl) azoxy]-benzonitrile Structure: N

NC

N

O

C5H11

O Thermophysical Properties: Solid → nematic 124°C Nematic → isotropic 153°C Analytical Properties: Complete separation of dichlorobenzene or bromotoluene isomers at 126°C; complete separation of chlorotoluene isomers at 87°C; partial separation of m- and p-xylenes at 87°C Reference: 13 Name: 4,4′-Bis-(p-methoxybenzylidene amino)-3,3′-dichloro biphenyl Structure: CI CH3O


CH

N

CI N

CH

OCH3


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → nematic 154°C Nematic → isotropic 344°C Analytical Properties: Separation of dimethylbenzene isomers, dihalobenzene isomers (Cl, Br), haloketone benzene isomers, dimethoxybenzene isomers Reference: 14 Name: Azoxybenzene p-cyano-p′-heptyl carbonate Structure: NC

N

N

O

O

O

C

O

C7H15

O

Thermophysical Properties: Solid → nematic 66°C Analytical Properties: Separation of disubstituted benzene isomers Reference: 15 Name: Azoxybenzene p-cyano-p′-octyl carbonate (mixed isomers) Structure: NC

N

N

O

O

O

C

O

C8H17

O

Thermophysical Properties: Solid → smectic 60.5°C Smectic → nematic 119.5°C Analytical Properties: Separation of ethyltoluenes, chlorotoluenes, bromotoluenes, dichlorobenzenes; also, ethylbenzenes from xylenes and propylbenzenes from ethylbenzenes Reference: 15 Name: Azoxybenzene p-cyano-p′-pentyl carbonate (pure isomer) Structure: NC

N

N

O

C

O

C5H11

O

O

Thermophysical Properties: Solid → nematic 60.5°C Nematic → isotropic 132°C Analytical Properties: Separation of ethyltoluenes, chlorotoluenes, bromotoluenes, dichlorobenzenes; also, ethylbenzenes from xylenes and propylbenzenes from ethylbenzenes Reference: 3 Name: Azoxybenzene p-cyano-p′-pentyl carbonate (mixed isomers) Structure: NC

N

N

O

O

O

C O

Thermophysical Properties: Solid → nematic 96–100°C Analytical Properties: Separation of disubstituted benzene isomers Reference: 15


O

C5H11


Mesogenic Stationary Phases (continued) Name: Cyanoazoxybenzene decyl carbonate Structure: NC

N

N

O

O

O

C

O

C10H21

O

Thermophysical Properties: Solid → smectic 74°C Smectic → isotropic 125.5°C Analytical Properties: Separation of polycyclic hydrocarbons Reference: 16 Name: Cyanoazoxybenzene hexyl carbonate (mixed isomers) Structure: NC

N

N

O

O

O

C

O

C6H13

O

C9H19

CH

CH

O

Thermophysical Properties: Solid → nematic 73–76°C Nematic → isotropic 137°C Analytical Properties: Separation of xylene and ethyltoluene isomers Reference: 16 Name: Cyanoazoxybenzene nonyl carbonate (mixed isomers) Structure: NC

N

N

O

O

O

C O

Thermophysical Properties: Solid → smectic 61°C Smectic → nematic 124°C Nematic → isotropic 127°C Analytical Properties: Separation of polycyclic hydrocarbons Reference: 16 Name: p-(p-Ethoxyphenylazo) phenyl crotonate Structure: O CH3CH2O

N

N

Thermophysical Properties: Solid → nematic 110°C Nematic → isotropic 197°C Analytical Properties: Separation of aromatic isomers Reference: 12


O

C

CH3


Mesogenic Stationary Phases (continued) Name: Carbonyl-bis-(D-leucine isopropyl ester) Structure: CH3 CH3

CH3 CH3

CH

CH

CH2

CH3 CH

O

CH3

C

*C

N

O

H

H

O

CH2

C

N

*C

C

H

H

O

CH3 O

CH CH3

Thermophysical Properties: Solid → smectic 55°C Smectic → isotropic 110°C Analytical Properties: Baseline and near-baseline separations of racemic mixtures of N-perfluoroacyl-2aminoethyl benzenes, trifluoroacetyl (TFA), pentafluoropropionyl (PFP), heptafluorobutyl (HFB) Reference: 17 Name: Carbonyl-bis-(L-valine isopropyl ester) Structure: CH3 CH3

CH

O

CH

CH3 O

CH3

C *C

N

O

H

H

CH3 CH3

C

CH

CH3

N *C

C

H

O

H

O

CH CH3

Thermophysical Properties: Solid → smectic1 91°C Note: This compound exhibits two stable smectic states Smectic1 → smectic2 99°C prior to melting Smectic2 → isotropic 109°C Analytical Properties: Separation of enantiomers Reference: 17 Name: Carbonyl-bis-(L-valine t-butyl ester) Structure: CH3 CH3

CH3 CH3

CH

CH

CH

O

CH2

CH3 O

CH3

C *C

N

O

H

H

C

CH2

CH3

N *C

C

H

O

H

O

CH CH3

Thermophysical Properties: Solid → smectic 98°C Smectic → isotropic 402°C Analytical Properties: Separation of enantiomers Reference: 17 Name: Carbonyl-bis-(L-valine ethyl ester) Structure: CH3 CH3 CH3

CH2

O

C *C

N

H

H

O


CH3 CH3 O

CH

C

CH N *C

C

H

O

H

O

CH2

CH3


Mesogenic Stationary Phases (continued) Thermophysical Properties: Solid → smectic 88°C Smectic → isotropic 388°C Analytical Properties: Separation of enantiomers Reference: 17 Name: Carbonyl-bis-(L-valine methylester) Structure: CH3 CH3

CH3 CH3 O

CH CH3

O

C *C

N

O

H

H

C

CH N *C

C

H

O

H

O

CH3

Thermophysical Properties: Solid → smectic 382°C Smectic → isotropic 415°C Analytical Properties: Separation of enantiomers Reference: 17 Name: Phenylcarboxylate ester (systematic name not available) Structure: CH3 CH3

Si

CH3 O

O CH3

Si

[CH2]5

O

CO

OCH3

O

O Si

[CH2]3

Si

CH3

O

CO

OCH3

O CH3

CH3 Thermophysical Properties: Solid → smectic 118°C Smectic → isotropic 300°C Analytical Properties: Separation of three- and four-member methylated polycyclic aromatic hydrocarbons (PAHs) on basis of length-to-breadth ratio (l/b); as l/b increases, retention time decreases; cross-linking increases retention times, separation of methylcrypene isomers Reference: 18 Name: p-Cyano-p′-octoxyazobenzene Structure: NC

N

N

O

C8H17

Thermophysical Properties: Solid → nematic 101°C Nematic → isotropic 111°C Analytical Properties: Separation of ethyltoluenes, chlorotoluenes, bromotoluenes, dichlorobenzenes; also, ethylbenzenes from xylenes and propylbenzene from ethylbenzenes Reference: 3



Mesogenic Stationary Phases (continued) Name: p-n-Butoxybenzoic acid Structure: COOH

OC4H9 Thermophysical properties: Solid → 100°C Mesomorphous → 150°C (not well characterized) Isotropic → 160°C Analytical Properties: Separation of methyl and monoalkyl substituted benzenes as well as organoelemental compounds (for example, dimethyl mercury) Reference: 19 Name: p-[(p-Methoxybenzylidene)-amino]phenylacetate Structure: CH3O CH

N

O O

C

CH3

Thermophysical Properties: Solid → nematic 80°C Nematic → isotropic 108°C Analytical Properties: Separation of substituted phenols; selectivity is best at the lower end of the nematic range Reference: 20 Name: Poly (mesogen/methyl) siloxane (PMMS) (compound has not been named) Structure:

CH3

Si

(CH2)3

O

OCH3

CO2

Thermophysical Properties: Solid → nematic 70°C Nematic → isotropic 300°C High thermal stability Analytical Properties: Separation of methylchrysene isomers Reference: 21 Name: N,N′-Bis-(p-butoxybenzylidene)-bis-p-toluidine (BBBT) Structure: C4H9O

CH

Thermophysical Properties: Solid → smectic 159°C Smectic → nematic 188°C Nematic → isotropic 303°C


N

CH2

CH2

N

CH

OC4H9


Mesogenic Stationary Phases (continued) Analytical Properties: Separation of polycyclic aromatic hydrocarbons on the basis of length-to-breadth ratio Reference: 23 Name: N,N′-Bis-(p-ethoxybenzylidene)-α,α′-bi-p-toluidine (BEBT) Structure: CH

C2H5O

N

CH2

N

CH2

CH

OC2H5

Thermophysical Properties: Solid → nematic 173°C Nematic → isotropic 341°C Analytical Properties: Separation of polynuclear aromatic hydrocarbons Reference: 24 Name: N,N′-Bis-(n-p-heptoxybenzylidene)-α,α′-bi-p-toluidine (BHpBT) Structure: C7H15O

φ

CH

N

φ

CH2

CH2

φ

N

CH

φ

OC7H15

φ

OC6H13

φ= Thermophysical Properties: Solid → smectic 119°C Smectic → nematic 238°C Nematic → isotropic 262°C Analytical Properties: Separation of polynuclear aromatic hydrocarbons Reference: 24 Name: N,N′-Bis-(n-p-hexoxybenzylidene)-α,α′-bi-p-toluidine (BHxBT) Structure: H13C6O

φ

CH

N

φ

CH2

CH2

φ

N

CH

φ= Thermophysical Properties: Solid → smectic 127°C Smectic → nematic 229°C Nematic → isotropic 276°C Analytical Properties: Separation of methyl and nitro derivatives of naphthalene; separation of higher hydrocarbons Reference: 25 Name: N,N′-Bis-(p-methoxybenzylidene)- α,α′-bi-p-toluidine (BMBT) Structure: CH3O

φ

CH

N

φ

CH2

CH2

φ

N

CH

φ

OCH3

φ= Thermophysical Properties: Solid → nematic 181°C Nematic → isotropic 320°C Analytical Properties: Separation of androstane and cholestane alcohols and ketones; good separation of azaheterocyclic compounds; column bleed of BMBT can occur during prolonged periods of operation of elevated temperatures Reference: 26



Mesogenic Stationary Phases (continued) Name: N,N-Bis-(n-octoxybenzylidene)-α,α′-bi-p-toluidine (BoBT) Structure: C8H17O

φ

CH

N

φ

CH2

CH2

φ

N

CH

φ

OC8H17

φ

OC5H11

φ= Thermophysical Properties: Solid → smectic 118°C Smectic → nematic 244°C Nematic → isotropic 255°C Analytical Properties: Separation of polynuclear aromatic hydrocarbons Reference: 24 Name: N,N-Bis-(p-n-pentoxybenzylidene)-α,α′-bi-p-toluidine (BPeBT) Structure: C5H11O

φ

CH

N

φ

CH2

CH2

φ

N

CH

φ= Thermophysical Properties: Solid → smectic 139°C Smectic → nematic 208°C Nematic → isotropic 283°C Analytical Properties: Separation of polynuclear aromatic hydrocarbons Reference: 24 Name: N,N′-Bis-(p-phenylbenzylidene)-α,α′-bi-p-toluidine (BphBT) Structure: O

CH

N

CH2

CH2

N

CH

O

Thermophysical Properties: Solid → nematic 257°C Nematic → isotropic 403°C Analytical Properties: Separation of unadulterated steroids; used chromatographically in the temperature range of 260–270°C Reference: 27 Name: N,N′-Bis-(p-n-propoxybenzylidene)-α,α′-bi-p-toluidine (BPrBT) Structure: C3H7O

φ

CH

N

φ

CH2

CH2

φ

N

CH

φ= Thermophysical Properties: Solid → smectic 169°C Smectic → nematic 176°C Nematic → isotropic 311°C Analytical Properties: Separation of polynuclear aromatic hydrocarbons Reference: 24


φ

OC3H7


Cholesteric Phases Name: Cholesteryl acetate Structure:

O CH3

C

O

Thermophysical Properties: Solid → cholesteric 94.5°C Cholesteric → isotropic 116.5°C Analytical Properties: Separation of aromatics and paraffins Reference: 28 Name: (S)-4′-[(2-Methyl-1-butoxy)carbonyl] biphenyl-4-yl 4-(allyloxy) benzoate Structure:

CH2

CH(CH2)aO

R

CO2 b

c

a=1 b=1 c=2 R = COOCH2C*H(CH3)CH2CH3 Thermophysical Properties: Solid → smectic 100°C Smectic → cholesteric 150°C Cholesteric → isotropic 188°C Analytical Properties: Suggested for separation of polycyclic aromatic compounds Reference: 11 Name: (S)-4′-[(2-Methyl-1-butoxy)carbonyl] biphenyl-4-yl 4-[4-(allyloxy) phenyl] benzoate Structure:

CH2

CH(CH2)aO

R

CO2 b

c

a=1 b=2 c=2 R = COOCH2C*H(CH3)CH2CH3 Thermophysical Properties: Solid → smectic 152°C Smectic → cholesteric 240°C Cholesteric → isotropic 278°C Analytical Properties: Suggested for separation of polycyclic aromatic compounds Reference: 11



Cholesteric Phases (continued) Name: (S)-4′-[(2-Methyl-1-butoxy)biphenyl-4-yl 4-(4-4-pentenyloxy) phenyl] benzoate Structure:

CH2

CH(CH2)aO

R

CO2 b

c

a=3 b=2 c=2 R = COOCH2C*H(CH3)CH2CH3 Thermophysical Properties: Solid → smectic 135°C Smectic → cholesteric 295°C Cholesteric → isotropic 315°C Analytical Properties: Suggested for separation of polycyclic aromatic compounds Reference: 11 Name: (S)-4-[(2-Methyl-1-butoxy)carbonyl]phenyl-4-[4-(allyloxy)phenyl] benzoate Structure:

CH2

CH(CH2)aO

R

CO2 b

c

a=1 b=2 c=1 R = COOCH2C*H(CH3)CH2CH3 Thermophysical Properties: Solid → smectic 118°C Smectic → cholesteric 198°C Cholesteric → isotropic 213°C Analytical Properties: Suggested for separation of polycyclic aromatic compounds Reference: 11 Name: Cholesterol cinnamate Structure:

CH

CH

C

O

O Thermophysical Properties: Solid → cholesteric 160°C Cholesteric → isotropic 210°C Analytical Properties: Separation of olefinic positional isomers Reference: 12, 29



Cholesteric Phases (continued) Name: Cholesterol-p-chlorocinnamate (CpCC) Structure:

Cl

CH

CH

C

O

O Thermophysical Properties: Solid → cholesteric 144°C Cholesteric → isotropic 268°C Analytical Properties: Separation of diastereomeric amides and carbamates; the separation of olefinic geometrical isomers is dependent upon the position of the double bond Reference: 29, 30 Name: Cholesterol-p-methylcinnamate Structure:

CH3

CH

CH

C

O

O Thermophysical Properties: Solid → cholesteric 157°C Cholesteric → isotropic 254°C Analytical Properties: Separation of olefinic positional isomers Reference: 29 Name: Cholesterol-p-methoxycinnamate Structure:

CH3O

CH

CH

C

O

O Thermophysical Properties: Solid → cholesteric 165°C Cholesteric → isotropic 255°C Analytical Properties: Separation of olefinic positional isomers Reference: 29



Cholesteric Phases (continued) Name: Cholesterol p-nitrocinnamate Structure:

O2N

CH

CH

C

O

O Thermophysical Properties: Solid → cholesteric 167°C Cholesteric → isotropic 265°C Analytical Properties: Separation of geometrical isomers (2- and 3-octadecene) using p-substituted cholesterols; (best separation) p-NO2 > p-MeO > cholesterol cinnamate > p-Me > p-Cl (worst separation) for unsaturation occurring within four carbon atoms from the terminal methyl; the above order holds for separations of tetradecen-1-ol acetates; for unsaturation on carbons 5–12 from the terminal methyl of the tetradecen-1-ol of acetates, the best separation is the reverse of the above Reference: 29 Name: Cholesteryl n-nonanoate Structure:

O CH3(CH2)7

C

O

Thermophysical Properties: Solid → smectic 77.5°C Smectic → cholesteric 80.5°C Cholesteric → isotropic 92°C Analytical Properties: Separation of aromatics and paraffins Reference: 28 Name: Cholesteryl n-valerate Structure:

O CH3(CH2)3

C

O

Thermophysical Properties: Solid → cholesteric 93°C Cholesteric → isotropic 101.5°C Analytical Properties: Separation of aromatics and paraffins Reference: 28



TRAPPING SORBENTS The following table provides a listing of the major types of sorbents used in sampling, concentrating, odor profiling, and air and water pollution research.1–6 These materials are useful in a wide variety of research and control applications. Many can be obtained commercially in different sizes, depending on the application involved. The purpose of this table is to aid in the choice of a sorbent for a given analysis. Information that is specific for solid phase microextraction (SPME) is provided elsewhere in this chapter.

REFERENCES 1. Borgstedt, H.U., Emmel, H.W., Koglin, E., Melcher, R.G., Peters, A., and Sequaris, J.M.L., Analytical Problems, Springer-Verlag, Berlin, 1986. 2. Averill, W. and Purcell, J.E., Concentration and gc determination of organic compounds from air and water, Chromatogr. Newslett., 6, 30, 1978. 3. Gallant, R.F., King, J.W., Levins, P.L., and Piecewicz, J.F., Characterization of Sorbent Resins for Use in Environmental Sampling, Report EPA-600/7-78-054, March 1978. 4. Chladek, E. and Marano, R.S., Use of bonded phase silica sorbents for the sampling of priority pollutants in waste waters, J. Chromatogr. Sci., 22, 313, 1984. 5. Good, T.J., Applications of bonded-phase materials, American Laboratory, July 1981, p. 36. 6. Beyermann, K., Organic Trace Analysis, Halsted Press (of John Wiley & Sons), New York, 1984.



Trapping Sorbents Sorbent

Desorption Solvents

Activated carbon

Carbon disulfide, methylene chloride, diethyl ether, diethyl ether with 1% methanol, diethyl ether with 5% 2propanol (caution: CS2 and CH3OH can react in the presence of charcoal)

Graphitized carbon-black

Carbon disulfide, methylene chloride, diethyl ether (or thermal desorption can be used)

Silica gel

Methanol, ethanol, water, diethyl ether

Activated alumina

Water, diethyl ether, methanol

Applications

Used for common volatile organics; examples include methylene chloride, vinyl chloride, chlorinated aliphatics, aromatics, acetates; more data are provided in the “Adsorbents for Gas Chromatography” table Notes: Metallic or salt impurities in the sorbent can sometimes cause the irreversible adsorption of electronrich oxygen functionalities; examples include 1-butanol, 2-butanone, and 2-ethoxyacetate; recovery rate is often poor for polar compounds Used for common volatile aliphatic and aromatic compounds, organic acids and alcohols, and chlorinated aliphatics; more data are provided in the “Adsorbents for Gas Chromatography” table Notes: These sorbents are hydrophobic and are not very sensitive to moisture; the possibility of thermal desorption makes them valuable for trace-level analyses

Used for polar compound collection and concentration; examples include alcohols, phenols, chlorophenols, chlorinated aromatics, aliphatic and aromatic amines, nitrogen dioxide; more data are provided in the “Adsorbents for Gas Chromatography” table Notes: Useful for compounds that cannot be recovered from the charcoal sorbents; the most serious problem with silica is the effect of water, which can cause desorption of the analytes of interest, and the heating effect involved can sometimes initiate reactions such as polymerization or hydrolysis of the analyte Used for polar compounds such as alcohols, glycols, ketones, aldehydes; has also been used for polychlorinated biphenyls and phthalates; more data are provided in the “Adsorbents for Gas Chromatography” table

Notes: Similar in application to silica gel Porous polymers

Hexane, diethyl ether, alcohols (thermal desorption also possible in some cases)

Used for a wide range of compounds, including phenols, acidic and basic organics, pesticides, priority pollutants; more data are provided in the “Porous Polymer Phases” table Notes: The most commonly used porous polymer sorbent is Tenax-GC, although the Porapak and Chromosorb Century series have also been used; Tenax-GC has been used with thermal desorption methods, but can release toluene, benzene, and trichloroethylene residues at higher temperatures; in addition to Tenax-GC, XAD 2-8, Porapak-N, and Chromosorbs 101, 102, 103, and 106 have found applications, sometimes in “stacked” sampling devices (for example, a sorbent column of Tenax-GC — Chromosorb 106 in tandem); Chromosorb 106, a very low polarity polymer, has the lowest retention of water with respect to organic materials and is well suited for use as a backup sorbent Bonded phases

Methanol, hexane, diethyl ether

Molecular sieves

Carbon disulfide, hexane diethyl ether

Used for specialized applications in pesticides, herbicides, and polynuclear aromatic hydrocarbons Notes: Most expensive of the common sorbents; useful for the collection of organic samples from water Used for the collection of aldehydes, alcohols, and acrolein Notes: Molecular sieve 13-X is the main molecular sieve to be used as a trapping adsorbent; the sorbents will also retain water



SORBENTS FOR THE SEPARATION OF VOLATILE INORGANIC SPECIES The following sorbents have proven useful for the adsorptive separation of volatile inorganic species.1

REFERENCES 1. MacDonald, J.C., Inorganic Chromatographic Analysis: Chemical Analysis Series, Vol. 78, John Wiley & Sons, New York, 1985.

Sorbents for the Separation of Volatile Inorganic Species Separation Material

Typical Separations

Alumina Beryllium oxide Silica gel Chromium(III) oxide Clay minerals (Attapulgite, Sepiolite) Kaolin Sodium-, lithium fluoride, alumina Quartz granules Chromosorb 102 Graphite Synthetic diamond Molecular sieve Carbon molecular sieve XAD resins Porapak Q Porapak QS polymers Porapak P Teflon

O2, N2, CO2 H2S, H2O, NH3 O2/N2, CO2, O3, H2S, SO2 O2, N2, Ar, He O2, N2, CO, CO2 He, O2, N2, CO, CO2 MoF6, SbF5, UF6, F Ta, Re, Ru, Os, Ir: oxides, hydroxides Element hydrides NH3, N2, H2 CF2O, CO2 Hydrogen isotopes O2, N2, CO, CO2, N2O, SO2, H2S NH3, SO2, H2S, CO, CO2, H2O GeH4, SnH4, AsH3, SbH3, Sn(CH3)4 H2S, CH3SH, (CH3)2S, (CH3)2SX, SO2 Chlorides of Si, Sn, Ge, P, As, Ti, V, Sb F, MoF6, SbF6, SbF3

From MacDonald, J.C., Inorganic Chromatographic Analysis: Chemical Analysis Series, Vol. 78, John Wiley & Sons, New York, 1985. With permission.



ACTIVATED CARBON AS A TRAPPING SORBENT FOR TRACE METALS Activated carbon, which is a common trapping sorbent for organic species, can also be used for trace metals.1 This material is typically used by passing the samples through a thin layer (50 to 150 mg) of the activated carbon that is supported on a filter disk. It can also be used by shaking 50 to 150 mg of activated carbon in the solution containing the heavy metal, and then filtering the sorbent out of the solution.

REFERENCES 1. Alfasi, Z.B. and Wai, C.M., Preconcentration Techniques for Trace Elements, CRC Press, Boca Raton, FL, 1992.

Activated Carbon as a Trapping Sorbent for Trace Metals Matrices Water Water

Water Water Water Water Water HNO3, water, Al, KCl Mn, MnO3, Mn salts Co, Co(NO3)2 Ni, Ni(NO3)2 Mg, Mg(NO3)2 Al Ag, TlNO3 Cr salts Co, In, Pb, Ni, Zn Se NaClO4

Trace Metals Ag, Bi, Cd, Co, Cu, Fe, In, Mg, Mn, Ni, Pb, Zn Ag, As, Ca, Cd, Ce, Co, Cu, Dy, Fe, La, Mg, Mn, Nb, Nd, Ni, Pb, Pr, Sb, Sc, Sn, U, V, Y, Zn Ba, Co, Cs, Eu, Mn, Zn Hg, methyl mercury Hg (halide) Hg (halide) U Ag, Bi, Cd, Cu, Hg, Pb, Zn Bi, Cd, Co, Cu, Fe, In, Ni, Pb, Tl, Zn Ag, Bi Ag, Bi Ag, Cu, Fe, Hg, In, Mn, Pb, Zn Cd, Co, Cu, Ni, Pb Bi, Co, Cu, Fe, In, Pb Ag, Bi, Cd, Co, Cu, In, Ni, Pb, Tl, Zn Ag, Bi, Cu, Tl Cd, Co, Cu, Fe, Ni, Pb, Zn Ag, Bi, Cd, Co, Cu, Fe, Hg, In, Mn, Ni, Pb

Complexing Agents (NaOH; pH 7–8) 8-Quinolinol

APDC, DDTC, PAN, 8-quinolinol — — — L-ascorbic acid Dithizone Ethyl xanthate APDC APDC (pH 8.1–9) Thioacetamide Xenol orange HAHDTC DDTC DDTC (pH 6)

Note: APDC = ammonium pyrrolidinecarbodithiolate; DDTC = diethyldithiocarbamate; HAHDTC = hexamethyleneammonium hexaethylenedithiocarbamate; PAN = 1-(2-pyridylazo)-2-naphthol.



REAGENT IMPREGNATED RESINS AS TRAPPING SORBENTS FOR TRACE MINERALS Reagent impregnated resins can be used as trapping sorbents for the preconcentration of heavy metals.1 These materials can be used in the same way as activated carbons.

REFERENCES 1. Alfasi, Z.B. and Wai, C.M., Preconcentration Techniques for Trace Elements, CRC Press, Boca Raton, FL, 1992.

Reagent Impregnated Resins as Trapping Sorbents for Trace Minerals Reagents TBP YBP DEHPA DEHPA Alamine 336 LIX-63 LIX-64N, -65N Hydroxyoximes Kelex 100 Kelex 100 Dithizone, STTA Dithizone (acetone) DMABR Pyrocatechol violet TPTZ

Adsorbents

Metals

Porous polystyrene DVB resins Levextrel (polystyrene DVB resins) Levextrel XAD-2 XAD-2 XAD-2 XAD-2 XAD-2 XAD-2 XAD-2, -4, -7, -8, -11 Polystyrene DVB resins XAD-1, -2, -4, -7, -8

U U Zn Zn U Co, Cu, Fe, Ni, etc. Cu Cu Co, Cu, Fe, Ni Cu Hg Hg, methyl mercury

XAD-4 XAD-2 XAD-2

Au In, Pb Co, Cu, Fe, Ni, Zn

Note: TBP = tributyl phosphate; DEHPA = diethylhexyl phosphoric acid; STTA = monothiothenolytrifluoroacetone; DMABR = 5-(4-dimethylaminobenzylidene)-rhodanine; TPTZ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine; LIX 63 = aliphatic α-hydroxyoxime; LIX 65N = 2hydroxy-5-nonylbenzophenoneoxime; LIX 64N = a mixture of LIX 65N with approximately 1% (v/v) of LIX-63.



7

REAGENT IMPREGNATED FOAMS AS TRAPPING SORBENTS FOR INORGANIC SPECIES Reagent impregnated foams can be used as trapping sorbents for the preconcentration of heavy metals.1 These materials can be used in the same way as activated carbons.

REFERENCES 1. Alfasi, Z.B. and Wai, C.M., Preconcentration Techniques for Trace Elements, CRC Press, Boca Raton, FL, 1992. Reagent Impregnated Foams as Trapping Sorbents for Inorganic Species Matrices Water Natural water Water Water

Elements 131

I,

203

Hg

Bi, Cd, Co, Cu, Fe, Hg, Ni, Pb, Sn, Zn Co, Fe, Mn

Concentration

Foam Type

Traces

Polyether

Alamine 336

Traces

Polyether

Amberlite LA-2

Traces to µg/L

PAN

µg/L µg/L Traces to µg/L µg/L µg/L

Natural water Water Water

Cd Au, Hg Ni Cr Hg, methyl-Hg, phenyl-Hg Sn Cd, Co, Fe, Ni Th

Polyether Polyether Polyether Polyether — Polyether Polyether

Traces Traces Traces

Polyether Polyether Polyether

Water

PO 3− 4

Traces

Natural water Water Water Water Water

Reagents

PAN PAN DMG, α-benzyldioxime DPC DADTC Toluene-3,4-dithiol Aliquot PMBP HDEHP-TBP Amine-molybdate-TBP

Note: PAN = 1-(2-pyridylazo)-2-naphthol; DMG = dimethylglyoxime; DPC = 1,5-diphenylcarbazide; DADTC = diethylammonium diethyldithiocarbamate; PMBP = 1-phenyl-3-methyl-4-benzoylpyrazolone-5; HDEHP = bis-[2-ethylhexyl]phosphate; TBP = tributyl phosphate.



CHELATING AGENTS FOR THE ANALYSIS OF INORGANICS BY GAS CHROMATOGRAPHY The following table provides guidance in choosing a chelating agent for the analysis of inorganic species by gas chromatography.1–3 The key to the abbreviation list is provided below.

REFERENCES 1. Guiochon, G. and Pommier, C., Gas Chromatography of Inorganics and Organometallics, Ann Arbor Science Publishers, Ann Arbor, MI, 1973. 2. Robards, K., Patsalides, E., and Dilli, S., Review: gas chromatography of metal beta-diketonates and their analogues, J. Chromatogr., 41, 1, 1987. 3. Robards, K. and Patsalides, E., Comparison of the liquid and gas chromatography of five classes of metal complexes, J. Chromatogr. A, 844, 181, 1999. acac dibm fod hfa tacac tfa thd tpm

= = = = = = = =

acetylacetonate 2,6-dimethyl-3,5-heptanedionate 1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedionate hexafluoroacetylacetonate monothioacetylacetonate trifluoroacetylacetonate 2,2,6,6-tetramethyl-3,5-heptadionate 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionate

Aluminum In Mixture With Complex

Beryllium In Mixture With Complex

Be, Sc Be Cr Be, Cr Be, Sc Be, Rh Cr, Rh Cr, Rh Cu, Fe Ga, In Fe Cr, Rh, Zr Be, Ga, In, Tl Be, Cr Be, Cr, Cu Be, Cr, Fe Be, Cu, Cr, Fe, Pd, Y Cr, Fe Cr, Fe, Cu Be, Cr, Fe, Ni Traces on U Traces

Al, Sc Cu Al, Cr Al, Sc Al, Ga, Tl, In Al, Cr Al, Cr, Cu Al. Cr, Fe Al, Cu, Cr, Fe, Pd, Y Al, Cr, Fe, Ni Traces


acac acac acac acac tfa tfa tfa tfa tfa tfa tfa tfa tfa hfa hfa hfa fod tpm tpm dibm tfa tfa, hfa

acac acac acac tfa tfa hfa hfa hfa fod dibm tfa


Chromium In Mixture With

Complex

Al, Be Al Al, Rh Al, Rh, Zr Al, Be Al, Be, Cu Al, Be, Fe Fe, Rh Ru Al, Fe Al, Fe, Cu Al, Be, Cu, Fe, Pd, Y Al, Be, Fe, Ni Traces in Fe Traces

acac acac tfa tfa hfa hfa hfa hfa hfa, tpm tpm tpm fod dibm tfa tfa, hfa

Copper In Mixture With

Complex

Be Al, Fe Fe Al, Be, Cr Fe Al, Cr, Fe Al, Be, Cr, Fe, Pd, Y

acac tfa tfa hfa hfa tpm fod

Indium In Mixture With

Complex

Al, Ga Al, Be, Ga, Tl

tfa tfa

Nickel In Mixture With Co, Pd Al, Be, Cr, Fe


Complex tacac dibm

Cobalt In Mixture With Complex Ru Ni, Pd Traces

tfa, hfa tacac fod

Gallium In Mixture With Complex Al, In Al, Be, In, Tl

Iron In Mixture With Al, Cu Al Cr Cu Al, Be, Cr Cu Cr, Rh Al, Cr Al, Cr, Cu Al, Be, Cr, Cu, Pd, Y Al, Be, Cr, Ni

tfa tfa

Complex tfa tfa tfa tfa hfa hfa hfa tpm tpm fod dibm

Paladium In Mixture With Complex A, Be, Cr, Cu, Fe, Y Co, Ni

fod tacac


Rare Earths In Mixture With

Complex

Sc Sc, Y Sc, Y Other rare earths

thd tpm fod hfa + tributylphosphate

Ruthenium In Mixture With

Complex

Co Cr

tfa, hfa hfa

Thallium In Mixture With

Complex

Al, Be, Ga, In

tfa Uranium

In Mixture With Th

Complex fod

Zirconium In Mixture With Al, Cr, Rh


Complex tfa

Rhodium In Mixture With Complex Al, Cr Al, Cr Al, Cr, Zr Cr, Fe Traces

tfa tfa tfa hfa tfa

Scandium In Mixture With Complex Al, Be Al, Be Rare earths Rare earths, Y Rare earths, Y

acac tfa thd tpm fod

Thorium In Mixture With Complex U

fod

Yttrium In Mixture With Complex Sc, rare earths Sc, rare earths Al, Be, Cr, Cu, Fe, Pd

tpm fod fod


BONDED PHASE MODIFIED SILICA SUBSTRATES FOR SOLID PHASE EXTRACTION The following table provides the most commonly used bonded phase modified silica substrates in solid phase extraction.1 Additional information on many of these materials can be found in the “More Common HPLC Stationary Phases” table in the HPLC chapter in this book.

REFERENCES 1. Fritz, J.S., Solid Phase Extraction, Wiley-VCH, New York, 1999.

Bonded Phase Modified Silica Substrates for Solid Phase Extraction Phase Octadecyl, endcapped Octadecyl Octyl Ethyl Cyclohexyl Phenyl Cyanopropyl Diol Silica gel Carboxymethyl Aminopropyl Propylbenzene sulfonic acid Trimethylaminopropyl

Polarity of Phase

Designation

Strongly apolar Strongly apolar Apolar Slightly polar Slightly polar Slightly polar Polar Polar Polar Weak cation exchanger Weak anion exchanger Strong cation exchanger Strong anion exchanger

C18ec C18 C8 C2 CH PH CN 2OH SiOH CBA NH2 SCX SAX

From Fritz, J.S., Solid Phase Extraction, Wiley-VCH, New York, 1999. With permission.



SOLID PHASE MICROEXTRACTION SORBENTS The following tables provide information on the selection and optimization of solid phase microextraction fibers.1 The reader is also advised to consult the tables for headspace analysis in this chapter.

REFERENCES 1. Shirey, R., Supelco Corp., Bellefonte, PA, 2003 (private communication).

FIBER SELECTION CRITERIA The main fiber selection parameters are polarity and relative molecular mass (RMM). This table provides general guidelines on the applicability of available fibers relative to these two parameters. The fibers are characterized by the extraction mechanism, either adsorption or absorption. Adsorbent fibers contain particles suspended in PDMS or Carbowax. Fiber Selection Criteria Fiber 7-µm PDMS 30-µm PDMS 85-µm polyacrylate 100-µm PDMS PDMS-DVB Carbowax-DVB PDMS-DVB-Carboxen PDMS-Carboxen

Type of Fiber

Polarity

RMM Range

Absorbent Absorbent Absorbent Absorbent Adsorbent Adsorbent Adsorbent Adsorbent

Nonpolar Nonpolar Polar Nonpolar Bipolar Polar Bipolar Bipolar

150–700 80–600 60–450 55–400 50–350 50–350 40–270 35–180

Note: PDMS = polydimethylsiloxane; DVB = divinylbenzene (3- to 5-µm particles); Carboxen = Carboxen 1006 (contains micro-, meso-, and macro-tapered pores; 3- to 5-µm particles). RMM range is ideal range for optimum extraction. Ranges can be extended by varying extraction times, but results will not be optimized.



EXTRACTION CAPABILITY OF SOLID PHASE MICROEXTRACTION SORBENTS This table shows the extraction capability of the fibers for acetone, a small, moderately polar analyte; 4-nitrophenol, a medium-size polar analyte; and benzo(GHI)perylene, a large nonpolar analyte. It provides a general guideline for fiber selection. Extraction Capability of Solid Phase Microextraction Sorbents

Fiber

Approximate Linear Concentration Range of Acetone, 10-Min Ext (FID)

Approximate Linear Concentration Range of 4-Nitrophenol, 20-Min Ext (GC/MS)

Approximate Linear Concentration Range of Benzo(GHI)perylene, 20-Min Ext

7-µm PDMS 30-µm PDMS 85-µm polyacrylate 100-µm PDMS PDMS-DVB Carbowax-DVB PDMS-DVB-Carboxen

100 ppm and up 10 ppm and up 1–1000 ppm 500 ppb–1000 ppm 50 ppb–100 ppm 100 ppb–100 ppm 25 ppb–10 ppm

Not extracted 10 ppm and up 5 ppb–100 ppm 500 ppb–500 ppm 25 ppb–10 ppm 5 ppb–10 ppm 50 ppb–10 ppm

100 ppt–500 ppb 100 ppt–10 ppm 500 ppt–10 ppm 500 ppt–10 ppm 10 ppb–1 ppm 50 ppb–5 ppm 100 ppb–1 ppm poorly desorbed Not desorbed

PDMS-Carboxen

5 ppb–5 ppm

100 ppb–10 ppm

Note: 1 ppm = 1 part in 1 × 10 ; 1 ppb = 1 part in 1 × 109; 1 ppt = 1 part in 1 × 1012. 6



SALTING OUT REAGENTS FOR HEADSPACE ANALYSIS The following table provides data on the common salts used for salting out in chromatographic headspace analysis, as applied to direct injection methods and to solid phase microextraction.1,2 Data are provided for the most commonly available salts, although others are possible. Sodium citrate, for example, occurs as the dihydrate and the pentahydrate. The pentahydrate is not as stable as the dihydrate, however, and dries out on exposure to air, forming cakes. Potassium carbonate occurs as the dihydrate, trihydrate, and sesquihydrate; however, data are provided only for the anhydrous material. The solubility is provided as the number of grams that can dissolve in 100 ml of water at the indicated temperature. The vapor enhancement cited is the degree of increase of the concentration of vapor over the solution of a 2% (mass/mass) ethanol solution in water at 60°C.3

REFERENCES 1. Lide, D.R., Ed., CRC Handbook of Chemistry and Physics, 83rd ed., CRC Press, Boca Raton, FL, 2002. 2. NIST Web Book, www.webbook.nist.gov/chemistry/, 2003. 3. Ioffe, B.V. and Vitenberg, A.G., Head Space Analysis and Related Methods in Gas Chromatography, Wiley Interscience, New York, 1983. Salting Out Reagents for Headspace Analysis

Salt Potassium carbonate Ammonium sulfate Sodium citrate (dihydrate) Sodium chloride Ammonium chloride a b c d e

Formula


Density

Solubility Cold Hot Water Water

Vapor Enhancement

K2CO3

138.21

2.428 at 14°C

112a

156b

8

(NH4)2SO4

132.13

1.769 at 50°C

70.6c

103.8b

5

Na3C6H5O7·2H2O

294.10

72d

167b

5

37.5a 29.7c

39.12b 75.8b

3 2

NaCl NH4Cl

20°C. 100°C. 0°C. 25°C. Specific gravity, 25/4°C.


58.44 53.49

2.165e 1.527


PARTITION COEFFICIENTS OF COMMON FLUIDS IN AIR–WATER SYSTEMS The following table provides the partition coefficients (or distribution coefficients), K = Cs/Cv (solid/vapor), at various temperatures, for application in gas chromatographic headspace analysis.1,2 The values marked with an asterisk were determined from a linear regression of experimental data.

REFERENCES 1. Ioffe, B.V. and Vitenberg, A.G., Head Space Analysis and Related Methods in Gas Chromatography, Wiley Interscience, New York, 1983. 2. Kolb, B. and Ettre, L.S., Static Headspace Gas Chromatography: Theory and Practice, Wiley-VCH, New York, 1996. Partition Coefficient, K Fluid Cyclohexane n-Hexane Tetrachloroethylene 1,1,1-Trichloromethane o-Xylene Toluene Benzene Dichloromethane n-Butyl acetate Ethyl acetate Methyl ethyl ketone n-Butanol Ethanol Dioxane m-Xylene n-Propanol Acetone


20°C

25°C

30°C

4.6 4.8

3.6 4.0

2.9 3.4

126 210 600 4660 7020 8000 5.9 5480 752

87 150 380 3600 5260 5750 4.0 4090 551

59 108 283 2710 4440 4330 3.9 3210 484

40°C 0.077 0.14 1.48 1.65 2.44 2.82 2.90 5.65 31.4 62.4 139.5 647 1355 1618

50°C

60°C

0.055* 0.068* 1.28* 1.53* 1.79* 2.23* 3.18* 4.29* 20.6* 42.7* 109* 384* 820* 1002*

0.040 0.043 1.27 1.47 1.31 1.77 2.27 3.31 13.6 29.3 68.8 238 511 624

479*


VAPOR PRESSURE AND DENSITY OF SATURATED WATER VAPOR The following table provides the temperature dependence of the saturated vapor pressure and vapor density of water. This information is useful in gas chromatographic headspace analysis and for SPME sampling.1,2

REFERENCES 1. Kolb, B. and Ettre, L.S., Static Headspace Gas Chromatography: Theory and Practice, Wiley-VCH, New York, 1997. 2. Lide, D.R., Ed., CRC Handbook of Chemistry and Physics, 83rd ed., CRC Press, Boca Raton, FL, 2002.

Vapor Pressure and Density of Saturated Water Vapor °C

p°(kPa)

p°(torr)

µg/ml) d (µ

10 20 30 40 50 60 70 80 90 100 110 120

1.2 2.3 4.2 7.4. 12.3 19.9 31.1 47.2 69.9 101.1 142.9 198.1

9.2 17.5 31.8 55.3 92.5 149.4 233.7 355.1 525.8 760.0 1074.5 1489.1

9.4 17.3 30.3 51.1 83.2 130.5 198.4 293.8 424.1 598.0 826.5 1122.0



DERIVATIZING REAGENTS FOR GAS CHROMATOGRAPHY The following table lists some of the more common derivatizing reagents used in gas chromatography for (1) increasing sample volatility, (2) increasing sample thermal stability, (3) reducing sample–support interactions, and (4) increasing sensitivity toward a particular detector. The table is divided into reagents for acylation, alkylation, esterification, pentafluorophenylation, and silylation. The conditions and concentrations used in derivatization must be carefully considered, since one can often cause more problems than one cures using these methods. Such problems include poor peak resolution, incomplete reactions and side products, and less than stoichiometric yields of products. Refer to the citation list for more details on the reagents, conditions, and difficulties.

REFERENCES General References 1. 2. 3. 4. 5. 6. 7.

Blau, K. and King, G.S., Eds., Handbook of Derivatives for Chromatography, Heyden, London, 1978. Knapp, D.R., Handbook of Analytical Derivatization Reactions, John Wiley & Sons, New York, 1979. Drozd, J., Chemical Derivatization in Gas Chromatography, Elsevier, Amsterdam, 1981. Poole, C.F. and Schutte, S.A., Contemporary Practice of Chromatography, Elsevier, Amsterdam, 1984. Grob, R.L., Modern Practice of Gas Chromatography, John Wiley & Sons, New York, 1985. Braithwaite, A. and Smith, F.J., Chromatographic Methods, Chapman & Hall, London, 1985. Merritt, C., in Ancillary Techniques of Gas Chromatography, Ettre, L.S. and McFadder, W.H., Eds., Wiley Interscience, New York, 1969. 8. Hammarstrand, K. and Bonelli, E.J., Derivative Formation in Gas Chromatography, Varian Aerograph, Walnut Creek, CA, 1968. 9. Vanden Heuvel, W.J.A., Gas Chromatography of Steroids in Biological Fluids, Plenum Press, New York, 1965.

Acylating Reagents 1. Brooks, C.J.W. and Horning, E.C., Gas chromatographic studies of catecholamines, tryptamines, and other biological amines, Anal. Chem., 36, 1540, 1964. 2. Imai, K., Sugiura, M., and Tamura, Z., Catecholamines in rat tissues and serum determined by gas chromatographic method, Chem. Pharm. Bull., 19, 409, 1971. 3. Scoggins, M.W., Skurcenski, L., and Weinberg, D.S., Gas chromatographic analysis of geometric diamine isomers as tetramethyl derivatives, J. Chromatogr. Sci., 10, 678, 1972.

Esterification Reagents 1. Shulgin, A.T., Separation and analysis of methylated phenols as their trifluoroacetate ester derivatives, Anal. Chem., 36, 920, 1964. 2. Argauer, R.J., Rapid procedure for the chloroacetylation of microgram quantities of phenols and detection by electron: capture gas chromatography, Anal. Chem., 40, 122, 1968. 3. Vanden Heuvel, W.J.A., Gardiner, W.L., and Horning, E.C., Characterization and separation of amines by gas chromatography, Anal. Chem., 36, 1550, 1964. 4. Änggård, E. and Göran, S., Gas chromatography of catecholamine metabolites using electron capture detection and mass spectrometry, Anal. Chem., 41, 1250, 1969. 5. Alley, C.C., Brooks, J.B., and Choudhary, G., Electron capture gas-liquid chromatography of short chain acids as their 2,2,2-trichloroethyl esters, Anal. Chem., 48, 387, 1976. 6. Godse, D.D., Warsh, J.J., and Stancer, H.C., Analysis of acidic monoamine metabolites by gas chromatography-mass spectrometry, Anal. Chem., 49, 915, 1977.



7. Matin, S.B. and Rowland, M., Electron-capture sensitivity comparison of various derivatives of primary and secondary amines, J. Pharm. Sci., 61, 1235, 1972. 8. Bertani, L.M., Dziedzic, S.W., Clarke, D.D., and Gitlow, S.E., A gas–liquid chromatographic method for the separation and quantitation of nomethanephrine and methanephrine in human urine, Clin. Chem. Acta, 30, 227, 1970. 9. Kawai, S. and Tamura, Z., Gas chromatography of catecholamines as their trifluoroacetates, Chem. Pharm. Bull., 16, 699, 1968. 10. Moffat, A.C. and Horning, E.C., A new derivative for the gas–liquid chromatography of picogram quantities of primary amines of the catecholamine series, Biochem. Biophys. Acta, 222, 248, 1970. 11. Lamparski, L.I. and Nestrick, T.J., Determination of trace phenols in water by gas chromatographic analysis of heptafluorobutyl derivatives, J. Chromatogr., 156, 143, 1978. 12. Mierzwa, S. and Witek, S., Gas-liquid chromatographic method with electron-capture detection for the determination of residues of some phenoxyacetic acid herbicides in water as their 2,2-trichloroethyl esters, J. Chromatogr., 136, 105, 1977. 13. Hoshika, Y., Gas chromatographic separation of lower aliphatic primary amines as their sulfurcontaining schiff bases using a glass capillary column, J. Chromatogr., 136, 253, 1977. 14. Brooks, J.B., Alley, C.C., and Liddle, J.A., Simultaneous esterification of carboxyl and hydroxyl groups with alcohols and heptafluorobutyric anhydride for analysis by gas chromatography, Anal. Chem., 46, 1930, 1974. 15. Deyrup, C.L., Chang, S.M., Weintraub, R.A., and Moye, H.A., Simultaneous esterification and acylation of pesticides for analysis by gas chromatography. 1. Derivatization of glyphosate and (aminomethyl) phasphonic acid with fluorinated alcohols-perfluoronated anhydrides, J. Agric. Food Chem., 33, 944, 1985. 16. Samar, A.M., Andrieu, J.L., Bacconin, A., Fugier, J.C., Herilier, H., and Faucon, G., Assay of lipids in dog myocardium using capillary gas chromatography and derivatization with boron trifluoride and methanols, J. Chromatogr., 339, 25, 1985.

Pentafluorobenzoyl Reagents 1. Mosier, A.R., Andre, C.E., and Viets, F.G., Jr., Identification of aliphatic amines volatilized from cattle feedyard, Environ. Sci. Technol., 7, 642, 1973. 2. DeBeer, J., Van Petegham, C., and Heyndridex, Al., Electron capture-gas–liquid chromatography (ECGLC) determination of the herbicidal monohalogenated phenoxyalkyl acid mecoprop in tissues, urine and plasma after derivatization with pentafluorobenzylbromide, Vet. Hum. Toxicol., 21, 172, 1979. 3. Davis, B., Crown ether catalyzed derivatization of carboxylic acids and phenols with pentafluorobenzyl bromide for electron capture gas chromatography, Anal. Chem., 49, 832, 1977. 4. Avery, M.J. and Junk, G.A., Gas chromatography/mass spectrometry determination of water-soluble primary amines as their pentafluorobenzaldehyde imines, Anal. Chem., 57, 790, 1985.

Silylating Reagents 1. Metcalfe, L.D. and Martin, R.J., Gas chromatography of positional isomers of long chain amines and related compounds, Anal. Chem., 44, 403, 1972. 2. Sen, H.P. and McGeer, P.L., Gas chromatography of phenolic and catecholic amines as the trimethylsilyl ethers, Biochem. Biophys. Res. Commun., 13, 390, 1963. 3. Fogelgvist, E., Josefsson, B., and Roos, C., Determination of carboxylic acids and phenols in water by extractive alkylation using pentafluorobenzylation, glass capillary g.c. and electron capture detection, HRC CC, J. High Resolut. Chromatogr. Chromatogr. Commun., 3, 568, 1980. 4. Poole, C.F.C., Sye, W.F., Singhawangcha, S., Hsu, F., Zlatkis, A., Arfwidsson, A., and Vessman, J., New electron-capturing pentafluorophenyldialkylchlorosilanes as versatile derivatizing reagents for gas chromatography, J. Chromatogr., 199, 123, 1980. 5. Quilliam, M.A., Ogilvie, K.K., Sadana, K.L., and Westmore, J.B., Study of rearrangement reactions occurring during gas chromatography of tert-butyl-dimethylsilyl ether derivatives of uridine, J. Chromatogr., 194, 379, 1980.



6. Poole, C.F. and Zlatkis, A., Trialkylsilyl ether derivatives (other than TMS) for gas chromatography and mass spectrometry, J. Chromatogr. Sci., 17, 115, 1979. 7. Francis, A.J., Morgan, E.D., and Poole, C.F., Flophemesyl derivatives of alcohols, phenols, amines and carboxylic acids and their use in gas chromatography with electron-capture detection, J. Chromatogr., 161, 111, 1978. 8. Harvey, D.J., Comparison of fourteen substituted silyl derivatives for the characterization of alcohols, steroids and cannabinoids by combined gas-liquid chromatography and mass spectrometry, J. Chromatogr., 147, 291, 1978. 9. Quilliam, M.A. and Yaraskavitch, J.M., Tertbutyldiphenylsilyl derivatization for liquid chromatography and mass spectrometry, J. Liq. Chromatogr., 8, 449, 1985.

Derivatizing Reagents for Gas Chromatography Derivatizing Reagent

Structure/Formula

Acetic anhydride

Acylating Reagents (CH3CO)2O Used for amino acids, steroids, urinary sugars, pesticides and herbicides, and narcotics

Chloracetic anhydride

(CH2ClCO)2O

α,p-Dibromoacetophenone

BrCH2

C

Notes

Useful for electron capture detection of lower aliphatic primary amines O

Used for short- and medium-chain aliphatic carboxylic acids

Br Heptafluorobutyric anhydride

(CF3CF2CF2CO)2O

Pentafluorobenzaldehyde F

O

Used in basic solution for alcohols, amines, nitrosamines, amino acids, and steroids; heptafluorobutylimidazole is used in a similar fashion in the analysis of phenols Useful for electron capture detection of several primary amines

CH

F

F

F F Pentafluorobenzoyl chloride

F

O

Useful for electron capture detection of several primary amines

CCl

F

F

F F Pentafluoropropionic anhydride Propionic anhydride


(CF3CF2CO)2O (CH3CH2CO)2O

Used for aromatic monoamines and their metabolites Used for amines, amino acids, narcotics


Derivatizing Reagents for Gas Chromatography Derivatizing Reagent

Structure/Formula

Pivalic anhydride

[(CH3)3CCO]2O

2-Thiophene aldehyde

Trifluoroacetic anhydride

Used for hormone analysis Used for electron capture detection of lower aliphatic primary amines

O S

Notes

CH

(CF3CO)2O

N-Trifluoroacetylimidazole

N CF3

C

N

Used for phenols, amines, amino acids, amino phosphoric acids, saccharides, and vitamins Useful for the relatively straightforward acylation of hydroxyl groups, secondary or tertiary amines

O Diazomethane

CH2=N=N + –

Trimethylanilinium hydroxide (TMAH) (in methanol)

Used as a common alkylating agent; acts on acidic and enolic groups rapidly, and more slowly on other groups with replaceable hydrogens (the use of a Lewis acid catalyst such as BF3 is sometimes helpful); all diazoalkanes are toxic and sometimes explosive, and are used in microscale operations only Useful for methylation of amines

−OH

+ N (CH3)3

Pentafluorobenzyl bromide

H2C

Br F

F

Useful for the derivatization of acids, amides, and phenols, providing great increase in sensitivity toward electron capture detection

F

F F

Boron trifluoride + methanol

Esterification Reagents BF3 + CH3OH Useful for carboxylic acids (aromatic and aliphatic), fatty acids, fatty acid esters, Krebs cycle acids

Boron trifluoride + n-propanol

BF3 + CH3(CH2)2OH

N,N-Dimethyl formamide dimethyl acetal

OCH3 HC

CH3

N

OCH3

Useful for fatty acid, lactic acid, and succinic acid

Useful in the formation of fatty acid esters and for N-protected amino acids, sulfonamides, barbiturates

CH3

2-Bromopropane

(CH3)2CHBr

Used for amino acids and amides

1-Butanol

CH3(CH2)3OH

Used for carboxylic acids and amino acids



Derivatizing Reagents for Gas Chromatography (continued) Derivatizing Reagent

Structure/Formula

Notes

Hydrogen chloride + methanol

HCl + CH3OH

Useful for carboxylic acids, branchedchain fatty acids, oxalic acid, amino acids, lipids; HCl serves as a catalytic agent

Sodium methoxide

CH3ONa in CH3OH

Used for the transesterification of lipids

Sulfuric acid + methanol

H2SO4 + CH3OH

Useful for carboxylic and fatty acids

Tetramethyl ammonium hydroxide

(CH3)4NOH in CH3OH

Useful for carboxylic acids, fatty acids, alkyd, and polyester resins

Thionyl chloride + alcohol

SOCl2

Useful in the formation of esters of carboxylic acids and other acidic functional groups

2,2,2-Trichloroethanol

Useful in the esterification of shortchain acids followed by electron capture detection; sometimes used with trifluoroacetic anhydride in the presence of H2SO4

H CCI3

C

OH

H Triethyl orthoformate Trimethylphenylammonium hydroxide

HC(OC2H5)3

Used for aminophosphoric acids

(CH3)3N+ − OH

α-Bromopentafluorotoluene F

in CH3OH

Used for fatty acids, aromatic acids, herbicides, pesticides

Pentafluorophenyl Reagents Used to etherify sterols and phenols, CH2Br in diethyl ether with the presence of potassium t-butoxide F

F

F F

Pentafluorobenzaldehyde

F F

F

F

F

Used in derivatizing primary amines; greatly enhances electron capture detector response (to the picogram level)

CHO Pentafluorobenzyl alcohol F

F

F

F H2COH


Used in derivatizing carboxylic acids in acidic medium

F



Structure/Formula

Pentafluorobenzyl bromide

F F

F

F

F

Notes Used in the derivatization of carboxylic acids, phenols, mercaptans, and sulfamides; lachrymator; potentially unstable; high sensitivity for electron capture detection; not usable for formic acid

COBr Pentafluorobenzyl chloride

F F

F

F

F

Used in the derivatization of amines, phenols, and alcohols; used in a solution of NaOH

CCI O Pentafluorobenzyl chloroformate

Used in the derivatization of tertiary amines

F F

F

F

F O CH2Cl

Pentafluorobenzyl hydroxylamine

F F

F

F

F

Used in derivatization of ketones; can form both syn- and anti-isomers (two peaks)

CH2NHOH Pentafluorophenacetyl chloride F

F

F

F H


Used in derivatization of alcohols, phenols, and amines

F

C

CCI

H

O



Structure/Formula

Pentafluorophenylhydrazine

Used in derivatization of ketones; can form both syn- and anti-isomers, resulting in two peaks

F F

F

F

F

Notes

NHNH2 Pentafluorophenoxyacetyl chloride

Used in derivatization of alcohols, phenols, and amines

F F

F

F

F O

CH2–C Cl O

Silylating Reagents Bis(dimethylsilyl)acetamide (BSDA)

CH3

C

N

Si (CH3)2

H

Si(CH3)3 O CH3 C

Bis(trimethylsilyl) trifluoroacetamide (BSTFA)

Dimethylchlorosilane (DMCS)

NSi(CH3)3 Si(CH3)3 O

CF3

C

NSi(CH3)3

H (CH3)2Si


Similar in use and application to DMCS (see below)

H

O

N,N-Bis(trimethyl-silyl)acetamide (BSA)

Si(CH3)2

CI

More reactive than HMDS (see below) or TMCS, but forming essentially similar derivatives; useful for alcohols, amines, amino acids, carboxylic acids, penicillic acid, purine and pyrimidene bases Similar in use and application to BSA, but the derivatives are more volatile; by-products often elute with the solvent front; reacts more strongly than HMDS or TMCS; may promote enol–TMS formation unless ketone groups are protected Similar in use and application to TMCS and HMDS, but usually forming more volatile and less thermally stable derivatives; also finds use in surface deactivation of chromatographic columns and injectors



Structure/Formula

Notes

1,1,1,3,3,3-Hexamethyl disilizane (HMDS)

(CH3)3 Si–NH–Si(CH3)3

Useful for such compounds as sugars, phenols, alcohols, amines, thiols, steroids; especially recommended for citric acid cycle compounds and amino acids; reaction is often carried out in pyridine or dimethyl formamide (the latter being preferred for 17-keto steroids); care must be taken to eliminate moisture; lowest silyl donating strength of all common silating reagents

1,1,1,3,3,3-Hexamethyl disiloxane (HMDSO)

(CH3)3Si–O–Si–(CH3)3

Similar in use and application to HMDS (see above)

N-Methyl-N-(trimethylsilyl)acetamide (MSTA)

CH3 CH3

C

N

Si(CH3)3

Similar in use and application to HMDS, but somewhat higher silyl donating strength

O N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA)

CH3 CF3

C

N

Si(CH3)3

O Tetramethyldisilazane (TMDS) H (CH3)2 Si N-Trimethylsilyl diethylamine (TMSDEA) N-Trimethylsilyl imidazole (TMSIM)


NH

N

(CH3)3SiCl

N

Similar in use and application to DMCS

Si (CH3)2

(CH3)3 Si–N (C2H5)2

(CH3)3 Si

Trimethylchlorosilane (TMCS)

H

Similar to MSTA, but produces the most volatile derivatives of all common silylating agents; particularly useful with lowmolecular-mass derivatives

Similar in use and application to DMCS Generally useful reagent with a high silyl donor ability; will not react with amino groups; will not cause formation of enol–ether on unprotected ketone groups; especially useful for ecdysones, norepinephrine, dopamine, steroids, sugars, sugar phosphates, and ketose isomers Similar properties and applications as for HMDS; useful for amino acid analyses; provides good response for electron capture detection; has relatively low silyl donating ability and is usually used in the presence of a base such as pyridine; may cause enol–ether formation with unprotected ketone groups; often used as a catalyst with other silylating reagents



Structure/Formula

Halomethylflophemesyl reagents

CH3 C6F5

Si

Y

R = CH2Cl

Notes Similar in use and applications to the flophemesyl and alkylflophemesyl reagents

Y = Cl

R Halomethyldimethyl silyl reagents

CH3 XCH2

Si

Y

CH3

Family of derivatizing agents that improve sensitivity of analyte to the electron capture detector; the response enhancement is in the order expected: I > Br > Cl >> F, reverse order of the volatility of these X = CI, Br, I compounds; the iodomethylY = CI, N(C2H5)2, NHSi(CH3)2CH2X dimethylsilyl reagents are unstable, and these derivatives are usually prepared in situ

Flophemesyl reagents CH3 C6F5

Si

Y

R = CH3 Y = CI, NH2, N(C2H5)2

R Alkylflophemesyl reagents

CH3 C6F5

Si

Y

R = CH(CH3)2, C(CH3)3 Y = CI

Family of reagents forming derivatives that have stabilities similar to those produced by TMSIM, BSA, MSTFA, and BSTFA, with additional electron capture detection sensitivity enhancement; usually used in pyridine as a solvent; reactions subject to steric considerations Family of reagents forming derivatives of somewhat higher stability than the flophemesyl reagents; reactions subject to steric considerations

R

Boronation reagents

Carbon disulfide Dansyl chloride

Miscellaneous Reagents (OH)2B–R R=CH3, –C(CH3)3, R2–CH3

CS2 SO2CI

Used to block two vicinal hydroxy groups; derivatives have very distinctive mass spectra that are easily identified Used to derivatize primary amines to yield isothiocyanates Used for derivatization of tripeptides; provides high sensitivity toward spectrofluorimetric detection

N(CH3)2 Dimethyldiacetoxysilane


(CH3)2Si(OOCCH3)2

Used in similar applications as the boronation reagents in pyridene or trimethylamine solvent



Structure/Formula

2,4-Dinitrophenylhydrazine

Notes Useful in derivatizing carbonyl compounds and also provides a spot test for these compounds

NHNH2 NO2

NO2 1-Fluoro-2,4-dinitrofluorobenzene

Useful for derivatizing C1–C4 primary and secondary amines, providing high electron capture detector response; this reagent is also useful for primary alicyclic amines

F NO2

NO2 Girard reagent T + (CH3)3N

O

− CI

Useful for derivatization of saturated aldehydes

CH2CNHNH2

Hydrazine

NH2NH2

Used for the analysis of C-terminal peptide residue species

Methyl iodide + silver oxide

CH3I + Ag2O (in dimethylformamide)

Used to convert polyhydroxy compounds to the methyl ethers

Methyloxamine hydrochloride

CH3–O–NH·HCl

Used in derivatization of steroids and carbohydrates

2-Methylthioanaline

Used to form sulfur-bearing derivatives of benzaldehydes

NH2 SCH3

Phenyl isocyanate N

2,4,6-Trichlorophenylhydrazine

HN CI

NH2 CI

CI


C

O

Used for derivatization of N-terminal peptide residue

Used for derivatization of carbonyl compounds


DETECTORS FOR GAS CHROMATOGRAPHY The following table provides some comparative data for the selection and operation of the more common detectors applied to capillary and packed column gas chromatography.1–7

REFERENCES 1. Hill, H.H. and McMinn, D., Eds., Detectors for Capillary Chromatography, Wiley Interscience, John Wiley & Sons, 1992. 2. Buffington, R. and Wilson, M.K., Detectors for Gas Chromatography: A Practical Primer, Hewlett Packard Corp., Avondale, PA, 1987. 3. Buffington, R., GC-Atomic Emission Spectroscopy Using Microwave Plasmas, Hewlett Packard Corp., Avondale, PA, 1988. 4. Liebrand, R.J., Ed., Basics of GC/IRD and GC/IRD/MS, Hewlett Packard Corp., Avondale, PA, 1993. 5. Bruno, T.J., A review of hyphenated chromatographic instrumentation, Sep. Purif. Methods, 29, 63, 2000. 6. Bruno, T.J., A review of capillary and packed column chromatographs, Sep. Purif. Methods, 29, 27, 2000. 7. Sevcik, J., Detectors in Gas Chromatography, Journal of Chromatography Library, Vol. 4, Elsevier, Amsterdam, 1976.


Detector

Limit of Detection

Linearity

Selectivity

Comments

Thermal conductivity detector (TCD), katharometer

1 × 10 g of propane (in helium carrier gas)

1 × 10

6

Universal response, concentration detector

Gas density balance detector (GADE)

1 × 10–9 g of H2 with SF6 as carrier gas

1 × 106

Universal response, concentration detector

Flame ionization detector (FID)

1 × 10–11 to 1 × 10–10 g

1 × 10–7

Organic compounds with C–H bonds

Nitrogen–phosphorus detector (NPD), thermionic detector, alkali flame ionization detector

4 × 10–13 to 1 × 10–11 g of nitrogen compounds 1 × 10–13 to 1 × 10–12 g of phosphorus compounds

1 × 10–4

105 to 106 by mass selectivity of N or P over carbon

• Ultimate sensitivity depends on analyte thermal conductivity difference with carrier gas • Since thermal conductivity is temperature dependent, response depends on cell temperature • Wire selection depends on chemical nature of analyte • Helium is recommended as carrier and makeup gas • Response and sensitivity is based on difference between relative molecular mass of analyte and that of the carrier gas; approximate calibration can be done on the basis of relative density • The sensing elements (hot wires) never touch sample, thus making GADE suitable for the analysis of corrosive analytes such as acid gases; goldsheathed tungsten wires are most common • Best used with SF6 as a carrier gas, switched with nitrogen when analyses are required • Detector can be sensitive to vibrations and should be isolated on a cushioned base • Ultimate sensitivity depends on the number of C–H bonds on analyte • Nitrogen is recommended as carrier gas and makeup gas to enhance sensitivity • Sensitivity depends on carrier, makeup, and jet gas flow rates • Column must be positioned 1–2 mm below the base of the flame tip • Jet gases must be of high purity • Does not respond to inorganic nitrogen such as N2 or NH3 • Jet gas flow rates are critical to optimization • Response is temperature dependent • Used for trace analysis only and is very sensitive to contamination • Avoid use of phosphate detergents or leak detectors • Avoid tobacco use nearby • Solvent quenching is often a problem


–10


Detectors for Gas Chromatography

Detector

Limit of Detection

Linearity

Selectivity

Comments

Selective for compounds with high electron affinity, such as chlorinated organics; concentration detector 105 to 1 by mass selectivity of S or P over carbon

• Sensitivity depends on number of halogen atoms on analyte • Used with nitrogen or argon/methane (95/5, mass/mass) carrier and makeup gases • Carrier and makeup gases must be pure and dry • The radioactive 63Ni source is subject to regulation and periodic inspection

Electron capture detector (ECD)

5 × 10 to 1 × 10–12 g

1 × 10

Flame photometric detector (FPD)

2 × 10–11 g of sulfur compounds 9 × 10–13 g of phosphorus compounds

1 × 103 for sulfur compounds 1 × 104 for phosphorus compounds

Photoionization detector (PID)

1 × 10–12 to 1 × 10–11 g

1 × 107

Depends on ionization potential of analytes

Sulfur chemiluminescence detector (SCD)

1 × 10–12 g of sulfur in sulfur compounds

1 × 104

107 by mass selectivity of S over carbon

Electrolytic conductivity detector (ECD, Hall detector)

10 × 10–13 to 1 × 10–12 g of chlorinated compounds 2 × 10–12 g of sulfur compounds 4 × 10–12 g of nitrogen compounds

1 × 106 for chlorinated compounds 104 for sulfur and nitrogen compounds

106 by mass selectivity of Cl over carbon 105 to 106 by mass selectivity of S and N over carbon


–14

4

• Hydrocarbon quenching can result from high levels of CO2 in the flame • Self-quenching of S and P analytes can occur with large samples • Gas flows are critical to optimization • Response is temperature dependent • Condensed water can be a source of window fogging and corrosion • Used with lamps with energies of 10.0–10.2 eV • Detector will have response to ionizable compounds such as aromatics and unsaturated organics, some carboxylic acids, aldehydes, esters, ketones, silanes, iodo- and bromoalkanes, alkylamines and amides, and some thiocyanates • Equimolar response to all sulfur compounds to within ±10% • Requires pure hydrogen and oxygen combustion gases • Instrument generates ozone in situ, which must be catalytically destroyed at detector outlet • Catalyst operates at 950–975°C • Detector operated at reduced pressure (103Pa) • Only high-purity solvents should be used • Carbon particles in conductivity chamber can be problematic • Frequent cleaning and maintenance is required • Often used in conjunction with a photoionization detector • For chlorine, use hydrogen as the reactant gas and n-propanol as the electrolyte


Detectors for Gas Chromatography (continued)

1 ×10–12 g

1 × 103 to 1 × 104

103

Mass selective detector (MSD), mass spectrometer (MS)

1 × 10–11 g (single-ion monitoring)

1 × 105

Universal

Infrared detector (IRD)

1 × 10–9 g of a strong infrared absorber

1 × 103

Universal for compounds with mid-infrared active functionality

Atomic emission detector (AED)

1 × 10–13 to 2 × 10–11 g of each element

1 × 103 to 1 × 104

103 to 105, element to element


1 × 10–8 g (scan mode)


Ion mobility detector (IMD)

• For nitrogen or sulfur, hydrogen or oxygen can be used as reactant gas, and water of methanol as the electrolyte • Ultra-high-purity reactant gases are required • Amenable to use in handheld instruments; linear dynamic range of 103 for radioactive sources and 105 for photoionization sources • Selectivity depends on mobility differences of ions • Has been used for a wide variety of compounds, including amino acids, halogenated organics, explosives • Quadrupole and magnetic sector instruments available • Must operate under moderate vacuum (1 × 10–4Pa) • Requires a molecular jet separator to operate with packed columns • Amenable to library searching for qualitative identification • Requires tuning of electronic optics over the entire m/e range of interest • See tables for mass spectrometry for structure elucidation and identification • A costly and temperamental instrument that requires high-purity carrier gas, a nitrogen purge of optical components (purified air will, in general, not be adequate) • Must be isolated from vibrations • Presence of carbon dioxide is a typical impurity band at 2200–2300 cm–1 • Requires frequent cleaning and optics maintenance • Amenable to library searching for qualitative identification • See tables for infrared functionalities for structure elucidation and identification • Requires the use of ultra-high-purity carrier and plasma gases • Plasma produced in a microwave cavity operated at 2450 MHz • Scavenger gases (H2,O2) are used as dopants • Photodiode array is used to detect emitted radiation


RECOMMENDED OPERATING RANGES FOR HOT WIRE THERMAL CONDUCTIVITY DETECTORS The following table provides guidance in the operation of hot wire thermal conductivity detectors. The operating trances are provided in mA dc for detector cells operated between 25 and 200°C.1 The current ranges and the cold resistances provided are for typical wire lengths and configurations.

REFERENCES 1. Gow-Mac Instrument Company Manual SB-13, Thermal Conductivity Detector Elements for Gas Analysis, Bethlehem, PA, 1995.

Carrier Gas Substance Tungsten, W Tungsten–rhenium, WX (97–3%) Nickel, Ni (99.8%) Gold-sheathed tungsten, AuW


H 2, mA-dc

He, mA-dc

N 2, mA-dc

CO2, Ar, mA-dc

Cold Resistance, Ohms, 25°°C

250–500 250–400

250–400 230–375

100–175 100–150

90–130 90–130

18 26–32

300–500 250–400

300–450 250–375

125–150 100–150

100–130 75–120

12.5 24


CHEMICAL COMPATIBILITY OF THERMAL CONDUCTIVITY DETECTOR WIRES The following table provides guidance in the selection of hot wires for use in thermal conductivity detectors (TCDs).1–3 This information is applicable to the operation of packed and open tubular columns. Some of the entries in this table deal with analytes, and others deal with solutions that might be used to clean the TCD cell.

REFERENCES 1. Gow-Mac Instrument Company Manual SB-13, Thermal Conductivity Detector Elements for Gas Analysis, Bethlehem, PA, 1995. 2. Seveik, J., Detectors in Gas Chromatography, Elsevier Scientific Publishing Co., Amsterdam, 1976. 3. Lawson, A.E. and Miller, J.M., Thermal conductivity detectors in gas chromatography, J. Gas Chromatogr., 4, 273, 1966.

Chemical Compatibility of Thermal Conductivity Detector Wires Substance

Tungsten (W)

Rhenium– Tungsten (WX)

Air/oxygen Water Steam

Good Good Good below 700°C Good

Good Good Good below 700°C Good

Good

Good

Good Good Poor (fluoride) forms at 20°C Fair Fair Fair Fair Fair Fair Fair Fair Poor

Ammonia/amines Carbon monoxide/carbon dioxide Hydrogen Nitrogen Fluorine Chlorine Bromine Iodine Sulfur Hydrogen sulfide/sulfur dioxide (sulfuric acid) Hydrogen chloride Aqua regia Hydrogen fluoride Hydrogen fluoride/nitric acid a

Nickel (Ni)

Gold-sheathed Tungsten (AuW)

Good Good Good

Very good Good Good

Poor in presence of water Good

Poora Good

Good Good Poor (fluoride) forms at 20°C Fair Fair Fair Good Fair

Good Good Good

Good Fair Poor

Good Good Good Poor Poor

Fair Fair Fair Good Good

Fair Fair Fair Poor

Good Poor Good Good

Fair Poor Fair Poor

Gold-sheathed tungsten filaments are attacked by amines, but the process is somewhat reversible. The baseline departure will recover, but the peak will develop a significant tail.



DATA FOR THE OPERATION OF GAS DENSITY DETECTORS The following data provide useful guidance in the operation and optimization of procedures with the gas density balance detector in gas chromatography.1 The property values were calculated with REFPROP.2

REFERENCES 1. Nerheim, A.G., A gas density detector for gas chromatography, Anal. Chem., 35, 1640, 1963. 2. Lemmon, E.W., McLinden, M.O., and Huber, M.L., NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties-REFPROP, Version 7.0, National Institute of Standards and Technology, Standard Reference Data Program, Gaithersburg, MD, 2002.

Data for the Operation of Gas Density Detectors Temperature, °C

Cp/Cv

Viscosity µPa-s

Argon, Ar, 24 psia 30 2.6251 60 2.3877 90 2.1899 120 2.0224 150 1.8787

1.6712 1.6703 1.6697 1.6692 1.6688

22.887 24.735 26.521 28.249 29.925

Carbon Dioxide, CO2, 24 psia 30 2.9120 60 2.6441 90 2.4221 120 2.2350 150 2.0749

1.2950 1.2802 1.2679 1.2576 1.2487

15.179 16.614 18.018 19.391 20.731

Helium, He, 24 psia 30 0.26258 60 0.23895 90 0.21923 120 0.20251 150 0.18816

1.6665 1.6665 1.6665 1.6665 1.6665

20.075 21.417 22.726 24.006 25.259

Hydrogen, H2, 24 psia 30 0.13222 60 0.12032 90 0.11039 120 0.10197 150 0.094745

1.4047 1.4015 1.3997 1.3987 1.3982

9.0188 9.6186 10.200 10.766 11.317

Nitrogen, N2, 24 psia 30 1.8396 60 1.6734 90 1.5348 120 1.4175 150 1.3169

1.4022 1.4013 1.4002 1.3989 1.3973

18.052 19.399 20.695 21.945 23.153


Density, g/L


Data for the Operation of Gas Density Detectors (continued) Temperature, °C

Density, g/L

Cp/Cv

Sulfur Hexafluoride, SF6, 24 psia 30 9.7615 1.0997 60 8.8401 1.0913 90 8.0832 1.0851 120 7.4489 1.0804 150 6.9090 1.0768 1,1,1,2-Tetrafluoroethane, R134a, 30 6.9186 60 6.2347 90 5.6842 120 5.2285 150 4.8436


Viscosity µPa-s

15.646 17.105 18.514 9.869 21.177

CF3CFH2, 24 psia 1.1247 12.013 1.1116 13.209 1.1021 14.365 1.0949 15.486 1.0890 16.575


PHASE RATIO FOR CAPILLARY COLUMNS The phase ratio is an important parameter used in the design of capillary (open tubular) column separations.1 This quantity relates the partition coefficient (K) to the partition ratio (k): K

=

kβ

where β is the phase ratio, defined as the ratio of the volume occupied by the gas or mobile phase (Vm) relative to that occupied by the liquid or stationary phase (Vs). For wall-coated open tubular columns, the phase ratio can be found from β

=

r/2df

where r is the internal radius of the column and df is the thickness of the stationary phase film. The following table provides the phase ratio for common combinations of column internal diameter and stationary phase film thickness. These values are given to the nearest whole number, since only an approximate value is needed for most analytical applications. REFERENCES 1. Sandra, P., High Resolution Gas Chromatography, Hewlett Packard Corp., Avondale, PA, 1989. Phase Ratio for Capillary Columns Column Inside Diameter, mm

Film Thickness, µm

0.05

0.10

0.20

0.30

0.32

0.40

0.50

0.53

0.03 0.06 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0

417 208 125 63 42 31 25 21 18 16 14 13 8 6.3 5 4 4 3 3 2.5 2 2 2 2 2 2 1 1

833 417 250 125 83 63 50 42 36 31 28 25 17 13 10 8 7 6 6 5 5 4 4 4 3 3 3 3

1667 833 500 250 167 125 100 83 71 63 56 50 34 25 20 17 14 13 11 10 9 8 8 7 7 6 6 6

2500 1250 750 375 250 188 150 125 107 94 83 75 50 38 30 25 21 19 17 15 14 13 12 11 10 9 9 8

2667 1333 800 400 267 200 160 133 114 100 89 80 53 40 34 27 23 20 18 16 15 13 12 11 11 10 9 9

3333 1667 1000 500 333 250 200 167 143 125 111 100 67 50 40 33 29 25 22 20 18 17 15 14 13 13 12 11

4167 2083 1250 625 417 313 250 208 179 156 139 125 83 63 50 42 18 32 29 25 23 21 19 18 17 16 15 14

4417 2208 1325 663 442 331 265 221 189 166 147 133 88 66 53 44 38 33 29 27 24 22 20 19 18 17 16 15



MARTIN–JAMES COMPRESSIBILITY FACTOR AND GIDDINGS PLATE HEIGHT CORRECTION FACTOR The following table provides the Martin–James compressibility factor, j,1 and the Giddings plate height correction factor, f,2 for chromatographically useful pressures. These quantities are defined as

[( [(

 P abs / P o  i j=3/2  abs  Pi / Po

[(

) )

] ]

−1   3  −1  

2

][(

4  abs abs  Pi / Po − 1 Pi / Po f =9/8  2 3  Piabs / Po − 1 

[(

)

]

)

)

2

]

 −1    

where Pi is the absolute inlet pressure and Po is the outlet pressure. The inlet pressures listed in the table are gauge pressures; the pressures used in the calculations of j and f are absolute pressures. Thus, atmospheric pressure had already been accounted for in the inlet pressure. The outlet pressure is taken as standard atmospheric pressure. As an example, for a measured gauge pressure of 137.9 kPa (20 psig), the ratio Piabs/Po is 2.361. The actual value of the atmospheric pressure will vary day to day, and with altitude; thus if an exact value for j or f is desired, local pressure measurements must be made.

REFERENCES 1. Grob, R.L., Modern Practice of Gas Chromatography, 2nd ed., John Wiley & Sons (Wiley Interscience), New York, 1985. 2. Lee, M.L., Yang, F.J., and Bartle, K.D., Open Tubular Column Gas Chromatography, John Wiley & Sons (Wiley Interscience), New York, 1984.

Martin–James Compressibility Factor and Giddings Plate Height Correction Factor


Pressure

j

f

15.0 16.0 17.0 18.0 19.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0

0.638 0.622 0.606 0.592 0.578 0.564 0.505 0.456 0.416 0.381 0.352 0.327 0.305 0.286

1.034 1.037 1.039 1.042 1.044 1.046 1.057 1.066 1.074 1.080 1.085 1.090 1.093 1.096


CRYOGENS FOR SUBAMBIENT TEMPERATURE GAS CHROMATOGRAPHY The following table lists properties of common cryogenic fluids used to produce subambient temperatures for gas chromatographic columns.1–5 These properties are of value in designing lowtemperature chromatographic experiments efficiently and safely. Due to the potential dangers in handling extremely low temperatures and high pressures, appropriate precautions must be observed. These precautions must include protective clothing and shielding to prevent frostbite. Most cryogenic fluids can create a health hazard if they are vaporized in an inhabited area. Even small quantities can contaminate and displace air in a relatively short period. It may be advisable to locate a self-contained breathing apparatus immediately outside the laboratory in which the cryogens are being used. The effect of low temperatures on construction materials (of GC ovens and columns, for example) should also be considered. In this respect, differential expansion and tensile strength changes are pertinent issues. A dew point vs. moisture content table is also provided to allow the user to estimate the effects of ambient and impure water. The viscosity data are provided in cP, which is equivalent to mPa⋅sec, the appropriate SI unit. The freezing points are reported at 0.101325 MPa (1 atm), and the expansion ratios are reported at STP. If temperatures no lower than approximately –40°C are required, the use of a Ranque–Hilsch vortex tube should be considered.6–8 This device requires a source of clean, dry compressed air at a pressure of approximately 0.70 MPa (100 psi) for proper operation. The flow rate of air that is required depends on the volume of space to be cooled.

REFERENCES 1. Zabetakis, M.G., Safety with Cryogenic Fluids, Plenum Press, New York, 1967. 2. Cook, G.A., Ed., Argon, Helium and the Rare Gases, John Wiley & Sons (Interscience) New York, 1961. 3. Brettell, T.A. and Grob, R.L., Cryogenic techniques in gas chromatography, Am. Lab., 17, 19, 1985. 4. Cowper, C.J. and DeRose, A.J., The Analysis of Gases by Chromatography, Pergamon Press, Oxford, 1983. 5. Matheson Gas Data Book, 7th ed., The Matheson Company, East Rutherford, NJ, 2001. 6. Bruno, T.J., Vortex cooling for subambient temperature gas chromatography, Anal. Chem., 58, 1596, 1986. 7. Bruno, T.J., Vortex refrigeration of HPLC components, Liq. Chromatogr. HPLC Mag., 4, 134, 1986. 8. Bruno, T.J., Laboratory applications of the vortex tube, J. Chem. Educ., 64, 987, 1987.



Cryogen Name Argon, Ar

39.948

Carbon dioxide, CO2 Helium, He

44.01

Methane, CH4

16.04

Nitrogen, N2

28.013

Oxygen, O2

31.999

Freezing Point, °C (K) –189.4 (83.8) −78.51 (194.7) −272b (1) −182.6 (90.6) −210.1 (63.1) −218.8 (54.4)

4.003

27.6 198.7 —b 58.6 25.5 13.8

Cryogen Name

Vapor Pressure, MPa

Argon, Ar

—a

1.63

860

Carbon dioxide, CO2 Helium, He

5.72 (21°C) —a

1.98

790

0.16

780

Methane, CH4

—a

0.7174

650

Nitrogen, N2

—a

1.14

710

Oxygen, O2

—a

1.3

875

a b

Gas Density, g/l

Heat of Fusion, J/g

Liquid/Gas Expansion Ratio

Normal Boiling Point, °C (K) –185.9 (87.3) −56.6 (216.6) −269.0 (4.2) −161.5 (87.3) −195.81 (77.3) −183.0 (90.2)

Heat of Vaporization, J/g 163.2 151.5 23.0 (15°C) 510.0 199.6 213.0

Critical Temperature, °C (K)

Critical Pressure, MPa

Critical Density, g/l

–122.3 (150.9) 31.1 (304.2) −268.0 (5.2) −82.1 (190.1) –146.9 (150.9) –118.4 (154.8)

4.89

530.5

7.38

468

0.23

69.3

4.64

162.5

3.4

311

5.04

410

Heat Capacity Cp, J/(kg·K)

Heat Capacity Cv , J/(kg·K)

Thermal Conductivity × 10–2 w/(m·K)

Viscosity Pa⋅⋅sec × 105 (cP)

Solubility in Water, 0°°C, v/v

523.8 (21°C) 831.8 (15.6°C) 5221.6 (21°C) 2205.4 (15.6°C) 1030.6 (21°C) 910.9 (15°C)

313.8 (15.6°C) 638.8 (15.6°C) 3146.4 (15.6°C) 1687.0 (15.6°C) 738.6 (21°C) 650.2 (15°C)

1.44 (233 K) 1.17 (233 K) 12.76 (233 K) 2.57 (233 K) 2.11 (233 K) 2.11 (233 K)

2.21 (21°C) 1.48 (21°C) 1.96 (21°C) 1.20 (21°C) 1.744 (15°C) 2.06 (20°C)

0.056 0.90 0.0086

0.023 0.0489

Fluid is supercritical at ambient temperature. Helium will not solidify at 1 atmosphere pressure (0.101325 MPa). The approximate pressure at which solidification can occur is calculated to be 2535 kPa.



Cryogens for Subambient Temperature Gas Chromatography


DEW POINT–MOISTURE CONTENT

Dew Point, °F –130 –120 –110 –105 –104 –103 –102 –101 –100 –99 –98 –97 –96 –95 –94 –93 –92 –91 –90 –89 –88 –87 –86 –85 –84 –83 –82 –81 –80 –79 –78 –77 –76 –75 –74 –73 –72 –71 –70 –69 –68 –67 –66 –65 –64 –63 –62 –61 –60


Dew Point, °C –90.0 –84.4 –78.9 –76.1 –75.6 –75.0 –74.4 –73.9 –73.3 –72.8 –72.2 –71.7 –71.7 –70.6 –70.0 –69.4 –68.9 –68.3 –67.8 –67.2 –66.7 –66.1 –65.6 –65.0 –64.4 –63.9 –63.3 –62.8 –62.2 –61.7 –61.1 –60.6 –60 –59.4 –58.9 –58.3 –57.8 –57.2 –56.7 –56.1 –55.6 –55.0 –54.4 –53.9 –53.3 –52.8 –52.2 –51.7 –51.1

Moisture, ppm (v/v) 0.1 0.25 0.63 1.00 1.08 1.18 1.29 1.40 1.53 1.66 1.81 1.96 2.15 2.35 2.54 2.76 3.00 3.28 3.53 3.84 4.15 4.50 4.78 5.30 5.70 6.20 6.60 7.20 7.80 8.40 9.10 9.80 10.50 11.40 12.30 13.30 14.30 15.40 16.60 17.90 19.20 20.60 22.10 23.60 25.60 27.50 29.40 31.70 34.00

1573_C02.fm Page 111 Friday, November 14, 2003 4:13 PM

CHAPTER

2

High-Performance Liquid Chromatography

CONTENTS Modes of Liquid Chromatography Solvents for Liquid Chromatography Instability of HPLC Solvents Ultraviolet Absorbance of Reverse Phase Mobile Phases Ultraviolet Absorbance of Normal Phase Mobile Phases Some Useful Ion-Pairing Agents Materials Compatible with and Resistant to 72% Perchloric Acid More Common HPLC Stationary Phases Eluotropic Values of Solvents on Octadecylsilane Mesh-Size Relationships Efficiency of HPLC Columns Column Failure Parameters Specialized Stationary Phases for Liquid Chromatography Chiral Stationary Phases for Liquid Chromatography Detectors for Liquid Chromatography Ultraviolet Detection of Chromophoric Groups Derivatizing Reagents for HPLC



MODES OF LIQUID CHROMATOGRAPHY The following flowchart provides a rough guide among the various liquid chromatographic techniques, based on sample properties. Low polarity

Reverse phase, Aqueous mobile phase

Nonionic Medium high polarity

Liquid, solid, or bonded phase

MC < 2000 Acidic Anion exchange/ion pair Ionic Sample

Basic

Cation exchange/ion pair

Water soluble

Steric exclusion, Aqueous mobile phase

Water insoluble

Steric exclusion, Nonaqueous mobile phase

MW > 2000

Courtesy of Millipore Corporation, Waters Chromatography Division, Billerica, MA.



SOLVENTS FOR LIQUID CHROMATOGRAPHY The following table provides the important physical properties for the selection of solvent systems for high-performance liquid chromatography (HPLC).1–7 These properties are required for proper detector selection, and the prediction of expected column pressure gradients. The values of the dielectric constant aid in estimating the relative solubilities of solutes and other solvents. Data on adsorption energies of useful HPLC solvents on silica and alumina (the eluotropic series) can be found in the chapter on thin-layer chromatography. Here we present the values for alumina, εo, not because this is a common surface encountered in HPLC, but because there are more data on this surface than for silica. These numbers should be used for trend analysis. The data presented were measured at 20°C, unless otherwise indicated (in parentheses). The solubility parameters, δ, defined fundamentally as the cohesive energy per unit volume, were calculated from vapor pressure data8 or estimated from group contribution methods.9 Those values obtained by group contribution are indicated by an asterisk.

REFERENCES 1. Willard, H.H., Dean, J.A., Settle, F.A., and Merritt, L.L., Instrumental Methods of Analysis, 7th ed., Wadsworth Publishing Co., Belmont, CA, 1995. 2. Snyder, L.R. and Kirkland, J.J., Introduction to Modern Liquid Chromatography, 2nd ed., John Wiley & Sons (Interscience), New York, 1979. 3. Dreisbach, R.R., Physical Properties of Chemical Compounds, Number 22 of the Advances in Chemistry Series, American Chemical Society, Washington, D.C., 1959. 4. Krstulovic, A.M. and Brown, P.R., Reverse Phase High Performance Liquid Chromatography, John Wiley & Sons (Interscience), New York, 1982. 5. Lide, D.R., Ed., CRC Handbook of Chemistry and Physics, 83rd ed., CRC Press, Boca Raton, FL, 2002. 6. Poole, C.F. and Shuttle, S.A., Contemporary Practice of Chromatography, Elsevier, Amsterdam, 1984. 7. Braithwaite, A. and Smith, F.J., Chromatographic Methods, 4th ed., Chapman & Hall, London, 1985. 8. Hoy, K.L, New values of the solubility parameters from vapor pressure data, J. Paint Technol., 42(541), 76, 1970. 9. Barton, A.F.M., Handbook of Solubility Parameters and Other Cohesion Parameters, 2nd ed., CRC Press, Boca Raton, FL, 1991.



Solvents for Liquid Chromatography

Solvent Acetic acid Acetone Acetonitrile Benzene 1-Butanol 2-Butanol n-Butyl acetate n-Butyl chloride Carbon tetrachloride Chlorobenzene Chloroform Cyclohexane Cyclopentane o-Dichlorobenzene N,N-Dimethylacetamide Dimethylformamide Dimethyl sulfoxide 1,4-Dioxane 2-Ethoxyethanol Ethyl acetate Ethyl ether Glyme (ethylene glycol dimethyl ether) n-Heptane n-Hexadecane n-Hexane Isobutyl alcohol Methanol 2-Methoxyethanol 2-Methoxyethyl acetate Methylene chloride Methylethylketone Methylisoamylketone Methylisobutylketone N-Methyl-2-pyrrolidone n-Nonane n-Pentane Petroleum ether β-Phenethylamine 1-Propanol 2-Propanol Propylene carbonate Pyridine Tetrachloroethylene Tetrahydrofuran Tetramethyl urea Toluene Trichloroethylene 1,1,2-Trichloro-1,2,2trifluoroethane 2,2,4-Trimethylpentane Water o-Xylene p-Xylene


εo 1.0 0.56 0.65 0.32

0.18 0.30 0.40 0.04 0.05

δ 13.01 9.62 12.11 9.16 11.60 11.08 8.69 8.37 8.55 9.67 9.16 8.19 8.10 10.04

0.62 0.56

11.79 12.8 10.13

0.58 0.38

8.91 7.53

0.01

7.50

0.01

7.27 11.24 14.50 11.68

0.95

0.42 0.51 0.43

0.00 0.01 0.82 0.82 0.71 0.45 0.29

0.01 Large 0.26

9.88 9.45 8.65 8.58 7.64 7.02

12.18 11.44 13.3 10.62 9.3 9.1

Viscosity, mPa·sec (20°C) 1.31 0.30 0.34 0.65 2.95 4.21 0.73 0.47 0.97 0.80 0.58 0.98 0.44 1.32 2.14 0.92 2.20 1.44 2.05 0.46 0.24 0.46

(15) (25) (25)

(15)

(25)

(15)

(25)

0.42 3.34 0.31 4.70 (15) 0.55 1.72 0.45 (15) 0.42 (15) 0.54 (25) 1.67 (25) 0.72 0.24 0.30 2.26 2.86 (15) 0.95 0.93 (15) 0.55

8.93 9.16

0.59 0.57 0.71

6.86 23.53 9.06

0.50 1.00 0.81

UV Cutoff, nm 330 190 278 215 260 254 220 263 287 245 200 200 295 268 268 286 215 210 256 218 220 200 200 200 220 205 210 254 233 329 330 334 285 200 200 226 285 210 205

Refractive Index (20°C)

Normal Boiling Point, °C

1.372 1.359 1.344 1.501 1.399 1.397 1.394 1.402 1.460 1.525 1.446 1.426 1.406 1.551 1.438 1.430 1.478 1.422 1.408 1.372 1.352 1.380

117.9 56.3 81.6 80.1 117.7 99.6 126.1 78.4 76.8 131.7 61.2 80.7 49.3 180.5 166.1 153.0 189.0 101.3 135.6 77.1 34.6 93.0

1.388 1.434 1.375 1.396 1.328 1.402 1.402 1.424 1.379 1.406 1.396 1.488 1.405 1.357

98.4 287.0 68.7 107.7 64.7 124.6 144.5 39.8 79.6 –144.0 116.5 202.0 150.8 36.1 30–60 197–198 97.2 82.3 240.0 115.3 121.2 66.0 175.2 110.6 87.2 47.6

330 295 212 265 284 273 231

1.529 (25) 1.386 1.377 1.419 1.510 1.506 1.407 1.449 (25) 1.497 1.477 1.356 (25)

215 2.5

0.94 >2.5

0.42 >2.5

0.21 >2.5

0.09 2.5

0.05 1.45

2.61 0.11

2.63 0.02

2.61 C=N−N >C

N

NHC

O

Primary amine, R–NH2

Active Polarographic Group

NH2

O

Hydroxylamine H2NOH

>C=N−OH

Oxime, >C=N–OH

Piperonal C8H6O3

C7H3O2–CH=N–R

Azomethine, >C=N–R

Carbon disulfide, CS2 R

N

S−

H

S C

Dithiocarbonate

N

C S−

H

S Cupric phosphate, Cu3(PO4)2, suspension

[Cu+2–amine] complex

Secondary amine, R2NH

Nitrous acid, HNO2

R2N–N=O

Primary alcohols, R–CH2OH

Chromic acid, HCrO4

[Cu+2–amine complex]

Nitroso, N

N

O

R–CHO

R Aldehyde carbonyl, C

O

H Secondary alcohols, R2–CH2OH

Chromic acid, HCrO4

R2C=O

R Ketone carbonyl, C

O

R 1,2-Diols

Periodic acid, HIO4 R

Aldehyde and/or ketone carbonyl >C=O

R C

O

H

C

O

R

Thiourea, (H2N)2C=S

RCO2 [(H2N)2CSH]+

Protonated thiocarbonyl, [>C=S–H]+

Phenyl, C6H5–, φ

Conc. nitric/conc. sulfuric acid, HNO3/H2SO4

C6H5NO2

Nitro, –NO2

Sulfides (thioethers), >S

Hydrogen peroxide, H2O2 or mchloroperbenzoic acid, 1,3-Cl-C6H4COOH

>S+→O−

Chloramine-T, CH3– φ –SO2NClNa

>S=NSO2–C6H4–CH3

Carboxylic acid, R C OH

–

O


Sulfoxide, S+

O−

Sulfilimine, >S=N–


COULOMETRIC TITRATIONS The following table lists some common coulometric (also known as constant-current coulometry) titrations.1–4 Since the titrant is generated electrolitically and reacted immediately, the method gets widespread applications. The generating electrolytic concentrations need to be only approximate, while unstable titrants are consumed as soon as they are formed. The technique is more accurate than methods where visual end points are required, such as in the case of indicators. The unstable titrants in the table below are marked with an asterisk.

REFERENCES 1. Christian, G.D., Analytical Chemistry, 5th ed., John Wiley & Sons, New York, 1994. 2. Christian, G.D., Electrochemical methods for analysis of enzyme systems, in Advances in Biomedical Engineering and Medical Physics, Vol. 4, Levine, S.N., Ed., Wiley Interscience, New York, 1971, p. 95. 3. Skoog, D.A., West, D.M., and Holler, J.F., Fundamentals of Analytical Chemistry, 6th ed., Saunders, Philadelphia, 1996. 4. Harris, D.C., Quantitative Chemical Analysis, 5th ed., W.H. Freeman, San Francisco, 1998.



Coulometric Titrations Generator Electrode Reaction

Reagent

Typical Generating Electrolyte

Ag+ Ag+2

Ag → Ag+ + e− Ag+ → Ag+2 + e−

Ag anode in HNO3

*Biphenyl radical anion *Br2

(C6H5)2 + e− → (C6H5)2−

Biphenyl/(CH3)4NBr in DMF 0.2 M NaBr in 0.1 M H2SO4

*BrO− Ce+4

2 Br− → Br2 + 2e−

Br − + 2 OH− → BrO−+ H2O + 2e− Ce+2 → Ce+4 + 2e−

*Cl2 *Cr+2 *CuCl3−2 EDTA

2 Cl− → Cl2 + 2e− Cr+3 + e− → Cr+2 Cu+2 + 3Cl− + e− → CuCl3−2 HgNH3(EDTA)+2 + NH4+ + 2e− → Hg + 2NH3 + (HEDTA)−3

EGTA

HgNH3(EGTA)+2 + NH4+ + 2e− → Hg + 2NH3 + (HEGTA)+1

Fe+2

Fe+3 + e− → Fe+2

I2

2I− → I2 + 2e−

H+

2H2O → 4H+ + O2 + 4e−

*Mn+3

Mn+2 → Mn+3+ e−

Mo+5

Mo+6 + e− → Mo+5

*MV+b OH−

MV+2 + e− → MV+ 2H2O + 2e− → H2 + 2OH−

Ti+3

Ti+4 + e− → Ti+3 or TiO+2 + 2H+ + e− → Ti+3 + H2O UO2+2 + 4H+ + 2e− → U+4 + 2H2O

U+4 a b

1 M NaBr in borate buffer, pH = 8.6a 0.1 M CeSO4 in 3 M H2SO4 Cr2(SO4)3 in H2SO4 0.1 M CuSO4 in 1 M HCl 0.02 M Hg+2/EDTA in ammoniacal buffer, pH = 8.5, Hg cathode 0.1 M Hg+2/EGTA in triethanolamine, pH = 8.6, Hg cathode Acid solution of FeNH4(SO4)2 0.2 M KI in pH = 8 buffer, pyridine, SO2, CH3OH, KI (Karl Fisher titration) 0.1 M Na2SO4 (water electrolysis) MnSO4 in 2 M H2SO4 0.7 M Mo+6 in 4 M H2SO4

Br−, Cl−, thiols Ce+3, V+4, H2C2O4, As+3 Anthracene As+3, Sb+3, U+4, Tl+, I−, SCN−, NH2OH, N2H4, phenols, aromatic amines, mustard gas, olefins, 8-hydroxyquinoline NH3 Fe+2, Ti+3, U+4, As+3, I−, Fe(SCN)6−4 As+3, I− O2 V+5, Cr+6,IO3− Ca+2, Cu+3, Zn+2, Pb+2 Ca+2 (in the presence of Mg+2) Cr+6, Mn+7, V+5, Ce+4 As+3, Sb+3, S2O3−2, H2S, H2O Pyridine H2C2O4, Fe+2, As+3, H 2O 2 Cr2O7−2 Mn+3 (in enzymes) HCl

0.1 M Na2SO4 (water electrolysis) 3.6 M TiCl4 in 7 M HCl

V+5, Fe+3, Ce+4, U+6

Acid solution of UO2+2

Cr+6, Ce+4

See page 573 for the preparation of this buffer. MV+ = methyl viologen radical cation; MV+2 = methyl viologen radical cation.


Substances Determined

+ CH3−N

+ N–CH3 + e−

+ CH3−N

N–CH3


CHAPTER

7

Ultraviolet Spectrophotometry

CONTENTS Solvents for Ultraviolet Spectrophotometry Ultraviolet Spectra of Common Liquids Transmittance–Absorbance Conversion Correlation Table of Ultraviolet Active Functionalities Woodward’s Rules for Bathochromic Shifts



SOLVENTS FOR ULTRAVIOLET SPECTROPHOTOMETRY The following table lists some useful solvents for ultraviolet spectrophotometry, along with their wavelength cutoffs and dielectric constants.1–6

REFERENCES 1. Willard, H.H., Merritt, L.L., Dean, J.A., and Settle, F.A., Instrumental Methods of Analysis, 7th ed., Van Nostrand, New York, 1988. 2. Strobel, H.A. and Heinemann, W.R., Chemical Instrumentation: A Systematic Approach, 3rd ed., John Wiley & Sons, New York, 1989. 3. Dreisbach, R.R., Physical Properties of Chemical Compounds, Advances in Chemistry Series 15, American Chemical Society, Washington, D.C., 1955. 4. Dreisbach, R.R., Physical Properties of Chemical Compounds, Advances in Chemistry Series 22, American Chemical Society, Washington, D.C., 1959. 5. Sommer, L., Analytical Absorption Spectrophotometry in the Visible and Ultraviolet, Elsevier Science, Amsterdam, 1989. 6. Krieger, P.A., High Purity Solvent Guide, Burdick and Jackson, McGaw Park, IL, 1984.



Solvents For Ultraviolet Spectrophotometry Solvent Acetic acid Acetone Acetonitrile Benzene sec-Butyl alcohol (2-butanol) n-Butyl acetate n-Butyl chloride Carbon disulfide Carbon tetrachloride Chloroforma Cyclohexane 1,2-Dichloroethane 1,2-Dimethoxyethane N,N-Dimethylacetamide N,N-Dimethylformamide Dimethylsulfoxide 1,4-Dioxane Diethyl ether Ethanol 2-Ethoxyethanol Ethyl acetate Methyl ethyl ketone Glycerol n-Hexadecane n-Hexane Methanol 2-Methoxyethanol Methyl cyclohexane Methyl isobutyl ketone 2-Methyl-1-propanol N-Methyl-2-pyrrolidone Pentane n-Pentyl acetate n-Propyl alcohol sec-Propyl alcohol Pyridine Tetrachloroethyleneb Tetrahydrofuran Toluene 1,1,2-Trichloro-1,2,2trifluoroethane 2,2,4-Trimethylpentane o-Xylene m-Xylene p-Xylene Water a b

Wavelength Cutoff, nm 260 330 190 280 260 254 220 380 265 245 210 226 240 268 270 265 215 218 210 210 225 330 207 200 210 210 210 210 335 230 285 210 212 210 210 330 290 220 286 231

6.15 20.7 (25°C) 37.5 2.284 15.8 (25°C)

215 290 290 290

1.936 (25°C) 2.568 2.374 2.270 78.54 (25°C)

Stabilized with ethanol to avoid phosgene formation. Stabilized with thymol (isopropyl meta-cresol).


Dielectric Constant (20°C)

7.39 (25°C) 2.641 2.238 4.806 2.023 10.19 (25°C) 59 (83°C) 36.7 4.7 2.209 (25°C) 4.335 24.30 (25°C) 6.02 (25°C) 18.5 42.5 (25°C) 2.06 (25°C) 1.890 32.63 (25°C) 16.9 2.02 (25°C)

32.0 1.844 20.1 (25°C) 18.3 (25°C) 12.3 (25°C) 7.6 2.379 (25°C)


ULTRAVIOLET SPECTRA OF COMMON LIQUIDS The following table presents, in tabular form, the ultraviolet spectra of some common solvents and liquids used in chemical analysis. The data were obtained using a 1.00 cm path length cell, against a water reference.1,2

REFERENCES 1. Krieger, P.A., High Purity Solvent Guide, Burdick and Jackson, McGaw Park, IL, 1984. 2. Sommer, L., Analytical Absorption Spectrophotometry in the Visible and Ultraviolet, Elsevier Science, Amsterdam, 1989

Ultraviolet Spectra of Common Liquids Acetone Wavelength, Maximum nm Absorbance 330 340 350 375 400

1.000 0.060 0.010 0.005 0.005

Acetonitrile Wavelength, Maximum nm Absorbance 190 200 225 250 350

1.000 0.050 0.010 0.005 0.005

2-Butanol Wavelength, Maximum nm Absorbance 260 275 300 350 400

1.000 0.300 0.010 0.005 0.005

n-Butyl Acetate Wavelength, Maximum nm Absorbance 254 275 300 350 400


1.000 0.050 0.010 0.005 0.005

Benzene Wavelength, Maximum nm Absorbance 278 300 325 350 400

1.000 0.020 0.010 0.005 0.005

1-Butanol Wavelength, Maximum nm Absorbance 215 225 250 275 300

1.000 0.500 0.040 0.010 0.005

Carbon Tetrachloride Wavelength, Maximum nm Absorbance 263 275 300 350 400

1.000 0.100 0.005 0.005 0.005

Chlorobenzene Wavelength, Maximum nm Absorbance 287 300 325 350 400

1.000 0.050 0.040 0.020 0.005


Ultraviolet Spectra of Common Liquids (continued) n-Butyl Chloride Wavelength, Maximum nm Absorbance 220 225 250 300 400

1.000 0.300 0.010 0.005 0.005

Cyclohexane Wavelength, Maximum nm Absorbance 200 225 250 300 400

1.000 0.170 0.020 0.005 0.005

Cyclopentane Wavelength, Maximum nm Absorbance 200 215 225 300 400

1.000 0.300 0.020 0.005 0.005

Decahydronaphthalene Wavelength, Maximum nm Absorbance 200 225 250 300 400

1.000 0.500 0.050 0.005 0.005

Dimethyl Formamide Wavelength, Maximum nm Absorbance 268 275 300 350 400

1.000 0.300 0.050 0.005 0.005

Dimethyl Sulfoxide Wavelength, Maximum nm Absorbance 268 275 300 350 400


1.000 0.500 0.200 0.020 0.005

Chloroform Wavelength, Maximum nm Absorbance 245 250 275 300 400

1.000 0.300 0.005 0.005 0.005

o-Dichlorobenzene Wavelength, Maximum nm Absorbance 295 300 325 350 400

1.000 0.300 0.100 0.050 0.005

Diethyl Carbonate Wavelength, Maximum nm Absorbance 256 265 275 300 400

1.000 0.150 0.050 0.040 0.010

Dimethyl Acetamide Wavelength, Maximum nm Absorbance 268 275 300 350 400

1.000 0.300 0.080 0.005 0.005

2-Ethoxyethanol Wavelength, Maximum nm Absorbance 210 225 250 300 400

1.000 0.500 0.200 0.005 0.005

Ethyl Acetate Wavelength, Maximum nm Absorbance 256 275 300 325 350

1.000 0.050 0.030 0.005 0.005


Ultraviolet Spectra of Common Liquids (continued) 1,4-Dioxane Wavelength, Maximum nm Absorbance 215 250 300 350 400

1.000 0.300 0.020 0.005 0.005

Ethylene Dichloride Wavelength, Maximum nm Absorbance 228 240 250 300 400

1.000 0.300 0.100 0.005 0.005

Ethylene Glycol Dimethyl Ether (Glyme) Wavelength, Maximum nm Absorbance 220 250 300 350 400

1.000 0.250 0.050 0.010 0.005

Heptane Wavelength, Maximum nm Absorbance 200 225 250 300 400

1.000 0.100 0.010 0.005 0.005

Methanol Wavelength, Maximum nm Absorbance 205 225 250 300 400

1.000 0.160 0.020 0.005 0.005

2-Methoxyethanol Wavelength, Maximum nm Absorbance 210 250 275 300 400


1.000 0.130 0.030 0.005 0.005

Diethyl Ether Wavelength, Maximum nm Absorbance 215 250 275 300 400

1.000 0.080 0.010 0.005 0.005

Hexadecane Wavelength, Maximum nm Absorbance 190 200 250 300 400

1.000 0.500 0.020 0.005 0.005

Hexane Wavelength, nm

Maximum Absorbance

195 225 250 275 300

1.000 0.050 0.010 0.005 0.005

Isobutanol Wavelength, Maximum nm Absorbance 220 250 275 300 400

1.000 0.050 0.030 0.020 0.010

Methyl-t-Butyl Ether Wavelength, Maximum nm Absorbance 210 225 250 300 400

1.000 0.500 0.100 0.005 0.005

Methylene Chloride Wavelength, Maximum nm Absorbance 233 240 250 300 400

1.000 0.100 0.010 0.005 0.005


Ultraviolet Spectra of Common Liquids (continued) 2-Methoxyethyl Acetate Wavelength, Maximum nm Absorbance 254 275 300 350 400

1.000 0.150 0.050 0.005 0.005

Methyl Isoamyl Ketone Wavelength, Maximum nm Absorbance 330 340 350 375 400

1.000 0.100 0.050 0.010 0.005

Methyl Isobutyl Ketone Wavelength, Maximum nm Absorbance 334 340 350 375 400

1.000 0.500 0.250 0.050 0.005

Methyl n-Propyl Ketone Wavelength, Maximum nm Absorbance 331 340 350 375 400

1.000 0.150 0.020 0.005 0.005

1-Propanol Wavelength, Maximum nm Absorbance 210 225 250 300 400

1.000 0.500 0.050 0.005 0.005

2-Propanol Wavelength, Maximum nm Absorbance 205 225 250 300 400


1.000 0.160 0.020 0.005 0.010

Methyl Ethyl Ketone Wavelength, Maximum nm Absorbance 329 340 350 375 400

1.000 0.100 0.020 0.010 0.005

n-Methylpyrrolidone Wavelength, Maximum nm Absorbance 285 300 325 350 400

1.000 0.500 0.100 0.030 0.010 Pentane

Wavelength, nm

Maximum Absorbance

190 200 250 300 400

1.000 0.600 0.010 0.005 0.005

β-Phenethylamine Wavelength, Maximum nm Absorbance 285 300 325 350 400

1.000 0.300 0.100 0.050 0.005

Pyridine Wavelength, Maximum nm Absorbance 330 340 350 375 400

1.000 0.100 0.010 0.010 0.005

Tetrahydrofuran Wavelength, Maximum nm Absorbance 212 250 300 350 400

1.000 0.180 0.020 0.005 0.005


Ultraviolet Spectra of Common Liquids (continued) Propylene Carbonate Wavelength, Maximum nm Absorbance 280 300 350 375 400

1.000 0.500 0.050 0.030 0.020

1,2,4-Trichlorobenzene Wavelength, Maximum nm Absorbance 308 310 350 375 400

1.000 0.500 0.050 0.010 0.005

Trichloroethylene Wavelength, Maximum nm Absorbance 273 300 325 350 400

1.000 0.100 0.080 0.060 0.060

1,1,2-Trichlorotrifluoroethane Wavelength, Maximum nm Absorbance 231 250 300 350 400


1.000 0.050 0.005 0.005 0.005

Toluene Wavelength, nm

Maximum Absorbance

284 300 325 350 400

1.000 0.120 0.020 0.050 0.005

2,2,4-Trimethylpentane Wavelength, Maximum nm Absorbance 215 225 250 300 400

1.000 0.100 0.020 0.005 0.005 Water

Wavelength, nm

Maximum Absorbance

190 200 250 300 400

0.010 0.010 0.005 0.005 0.005

o-Xylene Wavelength, Maximum nm Absorbance 288 300 325 350 400

1.000 0.200 0.050 0.010 0.005


TRANSMITTANCE–ABSORBANCE CONVERSION The following is a conversion table for absorbance and transmittance, assuming no reflection. Included for each pair is the percent error propagated into a measured concentration (using the Beer–Lambert law), assuming an uncertainty in transmittance of +0.005.1 The value of transmittance that will give the lowest percent error in concentration is 3.368. Where possible, analyses should be designed for the low uncertainty area.

REFERENCES 1. Kennedy, J.H., Analytical Chemistry Principles, Harcourt, Brace and Jovanovich, San Diego, 1984. Transmittance–Absorbance Conversion Transmittance

Absorbance

Percent Uncertainty

0.980 0.970 0.960 0.950 0.940 0.930 0.920 0.910 0.900 0.890 0.880 0.870 0.860 0.850 0.840 0.830 0.820 0.810 0.800 0.790 0.780 0.770 0.760 0.750 0.740 0.730 0.720 0.710 0.700 0.690 0.680 0.670 0.660 0.650 0.640 0.630 0.620 0.610 0.600 0.590 0.580

0.009 0.013 0.018 0.022 0.027 0.032 0.036 0.041 0.046 0.051 0.056 0.060 0.065 0.071 0.076 0.081 0.086 0.091 0.097 0.102 0.108 0.113 0.119 0.125 0.131 0.137 0.143 0.149 0.155 0.161 0.167 0.174 0.180 0.187 0.194 0.201 0.208 0.215 0.222 0.229 0.237

25.242 16.915 12.752 10.256 8.592 7.405 6.515 5.823 5.270 4.818 4.442 4.125 3.853 3.618 3.412 3.231 3.071 2.928 2.799 2.684 2.579 2.483 2.386 2.316 2.243 2.175 2.113 2.055 2.002 1.952 1.906 1.863 1.822 1.785 1.750 1.717 1.686 1.657 1.631 1.605 1.582



Transmittance–Absorbance Conversion (continued) Transmittance

Absorbance

Percent Uncertainty

0.570 0.560 0.540 0.530 0.520 0.510 0.500 0.490 0.480 0.470 0.460 0.450 0.440 0.430 0.420 0.410 0.400 0.390 0.380 0.370 0.360 0.350 0.340 0.330 0.320 0.310 0.300 0.290 0.280 0.270 0.260 0.250 0.240 0.230 0.220 0.210 0.200 0.190 0.180 0.170 0.160 0.150 0.140 0.130 0.120 0.110 0.100 0.090 0.080 0.070 0.060 0.050 0.040 0.030 0.020 0.010

0.244 0.252 0.268 0.276 0.284 0.292 0.301 0.310 0.319 0.328 0.337 0.347 0.356 0.366 0.377 0.387 0.398 0.409 0.420 0.432 0.444 0.456 0.468 0.481 0.495 0.509 0.523 0.538 0.553 0.569 0.585 0.602 0.620 0.638 0.657 0.678 0.699 0.721 0.745 0.769 0.796 0.824 0.854 0.886 0.921 0.958 1.000 1.046 1.097 1.155 1.222 1.301 1.398 1.523 1.699 2.000

1.560 1.539 1.502 1.485 1.470 1.455 1.442 1.430 1.419 1.408 1.399 1.391 1.383 1.377 1.372 1.367 1.364 1.361 1.359 1.358 1.359 1.360 1.362 1.366 1.371 1.376 1.384 1.392 1.402 1.414 1.427 1.442 1.459 1.478 1.500 1.525 1.553 1.584 1.619 1.659 1.704 1.756 1.816 1.884 1.964 2.058 2.170 2.306 2.473 2.685 2.961 3.336 3.881 4.751 6.387 10.852



CORRELATION TABLE FOR ULTRAVIOLET ACTIVE FUNCTIONALITIES The following table presents a correlation between common chromophoric functional groups and the expected absorptions from ultraviolet spectrophotometry.1–3 Although not as informative as infrared correlations, UV can often provide valuable qualitative information.

REFERENCES 1. Willard, H.H., Dean, J.A., Settle, F.A., and Merritt, L.L., Instrumental Methods of Analysis, 7th ed., Wadsworth Publishing Co., Belmont, CA, 1995. 2. Silverstein, R.M. and Webster, F.X., Spectrometric Identification of Organic Compounds, 6th ed., Wiley, New York, 1998. 3. Lambert, J.B., Shurvell, H.F., Lightner, D.A., Verbit, L., and Cooks, R.G., Organic Structural Spectroscopy, Prentice Hall, Upper Saddle River, NJ, 1998.


Chromophore Ether Thioether Amine Amide Thiol Disulfide Bromide Iodide Nitrile Acetylide (alkyne) Sulfone Oxime Azido Alkene Ketone Thioketone Esters Aldehyde Carboxyl Sulfoxide Nitro Nitrite Azo Nitroso Nitrate Conjugated hydrocarbon Conjugated Conjugated Conjugated Conjugated

hydrocarbon hydrocarbon hydrocarbon hydrocarbon

Conjugated hydrocarbon Conjugated system


Functional Group

γmax, nm

εmax

–O– –S– –NH2– –CONH2 –SH –S–S– –Br –I –C≡N –C≡C–

185 194 195 C=N– >C=C< >C=O >C=S –COOR –CHO –COOH >S→O –NO2 –ONO –N=N– –N=O –ONO2 –(C=C)2– (acyclic) –(C=C)3– –(C=C)4– –(C=C)5– –(C=C)2– (alicyclic) C=C–C≡C C=C–C=N

180 190 190 190 195 205 205 210 200–210 210 210 220–230 285–400 302 270 (shoulder) 210–230

— 5000 5000 8000 1000 Strong 50 Strong 50–70 1500 Strong 1000–2000 3–25 100 12 21,000

260 300 330 230–260

35,000 52,000 118,000 3000–8000

219 220

6500 23,000

γmax, nm

εmax

215

1600

255

400

270–285

18–30

280–300

11–18

300–4000

10

γmax, nm

εmax


Correlation Table for Ultraviolet Active Functionalities

Chromophore Conjugated system Conjugated system Benzene

Functional Group C=C–C=O C=C–NO2

γmax, nm 210–250 229 184

εmax 10,000–20,000 9500 46,700

Diphenyl

γmax, nm

εmax

202

6900

246

20,000

γmax, nm

εmax

300–350

Weak

255

170

312

175

Naphthalene

220

112,000

275

5600

Anthracene

252

199,000

375

7900

174

80,000

195

6000

251

1700

227

37,000

270

3600

314

2750

218

80,000

266

4000

317

3500

Pyridine

N

Quinoline

N Isoquinoline N



Correlation Table for Ultraviolet Active Functionalities (continued)


WOODWARD’S RULES FOR BATHOCHROMIC SHIFTS Conjugated systems show bathochromic shifts in their π→π* transition bands. Empirical methods for predicting those shifts were originally formulated by Woodward, Fieser, and Fieser.l–4 This section includes the most important conjugated system rules.l–5 The reader should consult references 5 and 6 for more details on how to apply the wavelength increment data.

REFERENCES 1. Woodward, R.B., Structure and the absorption spectra of α,β-unsaturated ketones, J. Am. Chem. Soc., 63, 1123, 1941. 2. Woodward, R.B., Structure and absorption spectra. III. Normal conjugated dienes, J. Am. Chem. Soc., 64, 72, 1942. 3. Woodward, R.B., Structure and absorption spectra. IV. Further observations on α,β-unsaturated ketones, J. Am. Chem. Soc., 64, 76, 1942. 4. Fieser, L.F. and Fieser, M., Natural Products Related to Phenanthrene, Reinhold, New York, 1949. 5. Silverstein, R.M. and Webster, F.X., Spectrometric Identification of Organic Compounds, 6th ed., Wiley, New York, 1998. 6. Lambert, J.B., Shurvell, H.F., Lightner, D.A., Verbit, L., and Cooks, R.G., Organic Structural Spectroscopy, Prentice Hall, Upper Saddle River, NJ, 1998.

Rules of Diene Absorption Base value for diene: 214 nm Increments for (each) (in nm): Heteroannular diene Homoannular diene Extra double bond Alkyl substituent or ring residue Exocyclic double bond Polar groups: –OOCR –OR –S–R Halogen –NR2 λ Calculated


+0 +39 +30 +5 +5 +0 +6 +30 +5 +60 = Total


Rules for Enone Absorptiona δ C

γ C

β C

α C

C O

Base value for acyclic (or six-membered) α,β-unsaturated ketone: 215 nm Base value for five-membered α,β-unsaturated ketone: 202 nm Base value for α,β-unsaturated aldehydes: 210 nm Base value for α,β-unsaturated esters or carboxylic acids: 195 nm Increments for (each) (in nm): Heteroannular diene +0 Homoannular diene +39 Double bond +30 Alkyl groups α– +10 β– +12 γ– and higher +18 Polar groups: –OH α– +35 β– +30 δ– +50 –OOCR α, β, γ, δ +6 –OR α– +35 β– +30 γ– +17 δ– +31 –SR β– +85 –Cl α– +15 β– +12 –Br α– +25 β– +30 –NR2 β– +95 Exocyclic double bond +5 λ Calculated a

= Total

Solvent corrections should be included. These are water (–8), chloroform (+1), dioxane (+5), ether (+7), hexane (+11), cyclohexane (+11). No correction for methanol or ethanol.



Rules for Monosubstituted Benzene Derivatives

Rules for Disubstituted Benzene Derivatives

Parent Chromophore (benzene): 250 nm

Parent Chromophore (benzene): 250 nm

Substituent

Increment

Substituent

o–

m–

p–

–4 –4 0 –16 –16 –16

–R –COR –OH –OR –O– –Cl –Br –NH2 –NHCOCH3 –NHCH3 –N(CH3)2

+3 +3 +7 +7 +11 +0 +2 +13 +20 — +20

+3 +3 +7 +7 +20 +0 +2 +13 +20 — +20

+10 +10 +25 +25 +78 (variable) +10 +15 +58 +45 +73 +85

–R –COR –CHO –OH –OR –COOR

Note: R is an alkyl group, and the substitution is on C6H5–.

Note: R indicates an alkyl group.


1573_C08.fm Page 319 Tuesday, November 25, 2003 11:32 AM

CHAPTER

8

Infrared Spectrophotometry

CONTENTS Infrared Optics Materials Internal Reflectance Element Characteristics Water Solubility of Infrared Optics Materials Wavelength–Wavenumber Conversion Table Useful Solvents for Infrared Spectrophotometry Polystyrene Wavenumber Calibration Infrared Absorption Correlation Charts Mid-Range Infrared Absorptions of Major Chemical Families Common Spurious Infrared Absorption Bands



INFRARED OPTICS MATERIALS The following table lists the more common materials used for optical components (windows, prisms, etc.) in the infrared region of the electromagnetic spectrum. The properties listed are needed to choose the materials with optimal transmission characteristics.1,2 The thermal properties are useful when designing experiments for operation at elevated temperatures.3–5 This listing is far from exhaustive, but these are the most common materials used in instrumentation laboratories.

REFERENCES 1. Gordon, A.J. and Ford, G.A., The Chemist’s Companion, John Wiley & Sons, New York, 1972. 2. Willard, H.H., Dean, J.A., Settle, F.A., and Merritt, L.L., Instrumental Methods of Analysis, 7th ed., Wadsworth, Belmont, CA, 1995. 3. Touloukien, Y.S., Powell, R.W., Ho, C.Y., and Klemens, P.G., Thermophysical Properties of Matter: Thermal Conductivity of Nonmetallic Solids, Vol. 2, IF — Plenum Data Corp., New York, 1970. 4. Touloukien, Y.S., Kirby, R.K., Taylor, R.E., and Lee, T., Thermophysical Properties of Matter: Thermal Expansion of Nonmetallic Solids, Vol. 13, IF — Plenum Data Corp., New York, 1977. 5. Wolfe, W.L. and Zissis, G.J., Eds., The Infrared Handbook, Mir, Moscow, 1995.


Refractive Index at 2 µm

Wavelength range, µm

Wavenumber range, cm–1

Sodium chloride, NaCl

0.25–16

40,000–625

1.52

7.61 (273 K) 6.61 (300 K) 4.85 (400 K)

0.448 (400 K) 0.896 (500 K)

Potassium bromide, KBr

0.25–25

40,000–400

1.53

Silver chloride, AgCl

0.4–23

25,000–435

2.0

Silver bromide, AgBr

0.50–35

20,000–286

2.2

Calcium fluoride, CaF2

0.15–9

66,700–1110

1.40

5.00 (275 K) 4.87 (301.5 K) 4.80 (372.2 K) 1.19 (269.8 K) 1.10 (313.0 K) 1.05 (372.5 K) 0.90 (308.2 K) 0.79 (353.2 K) 0.71 (413.2 K) 10.40 (237 K) 9.60 (309 K) 4.14 (402 K)

0.028 0.429 0.846 0.356 0.729 1.183 0.024 0.109 0.196 0.214 0.431 0.670

(400 (500 (600 (400 (500 (600 (300 (325 (350 (400 (500 (600

K) K) K) K) K) K) K) K) K) K) K) K)

Barium fluoride, BaF2

0.20–11.5

50,000–870

1.46

Cesium bromide, CsBr

1–37

10,000–270

1.67

0.233 0.461 0.698 0.526 1.063 1.645

(400 (500 (600 (400 (500 (600

K) K) K) K) K) K)

Cesium iodide, CsI

1–50

10,000–200

1.74

11.7 10.9 10.5 9.24 8.00 7.76 1.15 1.05 0.95

Thallium bromide–thallium iodide, TlBr–TlI (KRS–5) Zinc selenide, ZnSe

0.5–35

20,000–286

2.37

1–18

10,000–555

2.4

Germanium, Ge Silicon, Si

0.5–11.5 0.20–6.2

20,000–870 50,000–1613

4.0 3.5

Aluminum oxide (sapphire), Al2O3

0.20–6.5

50,000–1538

1.76

Polyethylene Mica Fused silica, SiO2

16–300 200–425 0.2–4.0

625–33 50–23.5 50,000–2500

1.54

a

Change in length divided by the starting length, × 100.


1.42 (at 3 µ m)

Thermal Conductivity, w/(m·K) × 102

Thermal Expansion, ∆L/L, percenta

Material

(284 K) (305 K) (370 K) (269.4 K) (337.5 K) (367.5 K) (277.7 K) (296.0 K) (360.7 K)

25.1 (293.2 K) 21.3 (323 K) 14.2 (432.2 K)

Notes Most common material; absorbs water; for aqueous solutions, use saturated NaCl solution as the solvent Useful for the study of C–Br stretch region; useful for solid sample pellets Not good for amines or liquids with basic nitrogen; light sensitive Not good for amines or liquids with basic nitrogen; light sensitive Useful for obtaining high resolution for –OH, N–H, and C–H stretching frequencies Shock sensitive, should be handled with care Useful for C–Br stretching frequencies Useful for C–Br stretching frequencies

0.464 1.026 0.086 0.175 0.272

(373 (473 (400 (500 (600

K) K) K) K) K)

0.033 0.066 0.102 0.075 0.148 0.225

(400 (500 (600 (400 (500 (600

K) K) K) K) K) K)

Highly toxic, handle with care; 42% TlBr, 58% TlI Vacuum deposited

Not useful for many organic compounds 1.38 (298 K)

Used in near infrared work; can be used with dilute and concentrated acids (except HF), not for use with aqueous alkali; metal ions can be problematic.


Infrared Optics Materials


INTERNAL REFLECTANCE ELEMENT CHARACTERISTICS Internal reflectance methods are a common sampling method in infrared spectrophotometry. The following table provides guidance in the selection of elements for reflectance methods.1

REFERENCES 1. Coleman, P., Practical Sampling Techniques for Infrared Analysis, CRC Press, Boca Raton, FL, 1993. Internal Reflectance Element Characteristics Material

Frequency Range (cm–1)

Index of Refraction

Thallium iodide–thallium bromide (KRS-5)

16,000–250

2.37

Zinc selenide (Irtran-4)

20,000–650

2.4

Zinc sulfide (Cleartran)

50,000–770

2.2

Cadmium telluride (Irtran-6) Silicon

10,000–450

2.6

9000–1550

3.5

Germanium

5000–850

4.0

Diamond

4000–400

2.46


Characteristics Relatively soft, deforms easily; warm water, ionizable acids and bases, chlorinated solvents, and amines should not be used with this ATR element Brittle; releases H2Se, a toxic material, if used with acids; water insoluble; electrochemical reactions with metal salts or complexes are possible Reacts with strong oxidizing agents; relatively inert with typical aqueous, normal acids and bases and organic solvents; good thermal and mechanical shock properties; low refractive index causes spectral distortions at 45°C Expensive; relatively inert; reacts with acids Hard and brittle; useful at temperatures to 300°C; relatively inert Hard and brittle; temperature opaque at 125°C Extremely robust element, not brittle unless used as a composite with other materials; note that diamond absorbs at 2500–1900, thus producing a gap in the spectrum that cannot be measured.


WATER SOLUBILITY OF INFRARED OPTICS MATERIALS The following table provides guidance in the selection of optics materials.1 Often, the solubility in (pure) water of a particular material is of critical concern.

REFERENCES 1. Coleman, P., Practical Sampling Techniques for Infrared Analysis, CRC Press, Boca Raton, FL, 1993. Water Solubility of Infrared Optics Materials Material Sodium chloride Potassium bromide Potassium chloride Cesium iodide Fused silica Calcium fluoride Barium fluoride Thallium bromide–iodide (KRS-5) Silver bromide Zinc sulfide Zinc selenide (Irtran-4) Polyethylene (high density)


Formula

Solubility, g/100 g H2O at 20°C

NaCl KBr KCl CsI SiO2 CaF2 BaF2 — AgBr ZnS ZnSe —

36.0 65.2 34.7 160(at 61°C) Insoluble 1.51 × 10–3 0.12(at 25°C) CH2 (sym): 2860–2840 (s)

Below 1500 (w/m/s) CH3– (asym): 1460–1440 (s) CH3– (sym): 1380–1370 (s) >CH2 (scissoring): ~1465 (s) >CH2 (rocking): ~720 (s) >CH2 (twisting and wagging): 1350–1150 (w)

C–H (3°): ~2890 (vw)

gem Dimethyl [(CH3)2CH–]: 1380, 1370 (m, symmetrical doublet) tert-Butyl [(CH3)3C–]: 1390, 1370 (m, asymmetrical doublet; latter more intense) CH3– rocking: 930–920 (w, not reliable)

Same as in acyclic alkanes; ring strain increases the wavenumbers up to 3100 cm–1

>CH2 (scissoring): lower than in acyclic alkanes (10–15 cm–1)

R2

Cyclic (CH2)n


Wavenumbers (cm–1) C–H Bend

C–C Stretch

C–C Bend

1200–800 (w) (not of practical value for definitive assignment)

Below 500 (not of practical value for definitive assignment)


Hydrocarbon Compounds

Family Alkenes (olefins) Acyclic Nonconjugated Monosubstituted (vinyl) Disubstituted cis-

trans-

Vinylidene

Trisubstituted

Tetrasubstituted


General Formula

>C=C< Stretch

Wavenumbers (cm–1) >C=C–H >C=C–H Bend Stretch (In-Plane)

>C=C–H Bend (Out-of-Plane)

Notes

CnH2n

1670–1600

Above 3000

R1CH=CH2

1667–1640 (m) 1658–1648 (m)

3082–3000 (m)

1420–1415 (m) (scissoring)

~995 (m) ~919 (m)

1662–1652 (m)

3030–3015 (m)

~1406 (m)

715–675 (s) (rocking)

C–H rocking not dependable for definitive assignment

1678–1668 (w)

3030–3020 (m)

1325–1275 (m) (deformation)

~965 (s) (rocking)

>C=C< stretch may not be detected due to symmetry

1658–1648 (m)

3090–3080 (m) ~2980 (m)

~1415 (m)

~890 (s) (rocking)

1675–1665 (w)

3090–3080 (w)

~1415 (w)

840–800 (m) (deformation)

R1 >C H

R2 C
C H

C
C R2

C
C R2

C
C R2

H H H R3 R3 C< R4

~1670 (vw)

—

—

—

>C=C< stretch may not be detected due to symmetry


Hydrocarbon Compounds (continued)

>C

Cumulated Cyclic

C

C

C
C=C=C
C=C< with an aromatic ring raises the frequency by 20–25 cm–1

>C=C< stretch is coupled with C–C stretch of adjacent bonds; alkyl substitution increases the >C=C< absorption frequency >C=C< frequency increases with decreasing ring size


Conjugated

≡C– Stretch –C≡

Family

General Formula

Alkynes Nonconjugated

CnH2n–2

Terminal

R1–C≡C–H

2150–2100 (m)

Nonterminal

R1–C≡C–R2

2260–2190 (vw)

Conjugated Terminal

R1–C≡C–C≡C–H

Nonterminal

R1–C≡C–C≡C–R2


Wavenumbers (cm–1) ≡C–H –C≡ Stretch

C–H Bend

Notes

3310–3200 (m) (sharp)

700–610 (s) 1370–1220 (w) (overtone)

–C≡C–H stretch peak is narrower than that of –OH or –NH stretch, which are broader due to hydrogen bonding

—

700–610 (s) 1370–1220 (w) (overtone)

2200, 2040 (doublet)

3310–3200 (m) (sharp)

700–610 (s) 1370–1220 (w) (overtone)

2200, 2040 (doublet)

—

700–610 (s) 1370–1220 (w) (overtone)



Family

General Formula

H>C=C< Stretch

Wavenumbers (cm–1) >C=C< Stretch

>C–H Bend (Out-of-Plane)

Aromatic compounds

All show weak combination and overtone bands between 2000 and 16,500 cm–1; see aromatic substitution pattern chart

Monosubstituted

3100–3000

1600–1500

770–730 (s) 710–690 (s)

Disubstituted 1,2-

3100–3000

1600–1500

770–735 (s)

1,3-

3100–3000

1600–1500

810–750 (s) 710–690 (s)

1,4-

3100–3000

1600–1500

833–810 (s)

Trisubstituted 1,2,3-

3100–3000

1600–1500

780–760 (s) 745–705 (m)


Notes



Family

General Formula

H>C=C< Stretch


>C–H Bend (Out-of-Plane)

1,2,4-

3100–3000

1600–1500

885–860 (m) 825–805 (s)

1,3,5-

3100–3000

1600–1500

865–810 (s) 730–765 (m)

Tetrasubstituted 1,2,3,4-

3100–3000

1600–1500

810–800

1,2,3,5-

3100–3000

1600–1500

850–840


Notes



3100–3000

1600–1500

870–855

Pentasubstituted

3100–3000

1600–1500

~870

Hexasubstituted

3100–3000

1600–1500

Below 500



1,2,4,5-

Wavenumbers (cm–1) Family

General Formula

Acetals

O–H Stretch

H

C

–O–H Bend

Notes

1195–1060 (s) (three bands) 1055–1040 (s) (sometimes obscured)

OR2 R1

>C–O Stretch

OR3 Acyl halides

R–C(=O)X X = halogen

Alcohols

R–OH

Primary

R–CH2OH

Secondary R1

CHOH R2

Tertiary R2 R1

C R3


OH

See Organic Halogen Compounds 3650–3584 (s, sharp) for very dilute solutions or vapor phase spectra 3550–3200 (s, broad) for less dilute solutions where intermolecular hydrogen bonding is likely to occur Intramolecular hydrogen bonding is responsible for a broad, shallow peak in the range of 3100–3050 cm–1

1420–1300(s) ~1050

~1420 (m) and ~1330 (m) (coupling of O–H in-plane bending and C–H wagging)

~1100

~1420 (m) and ~1330 (m) (coupling of O–H in-plane bending and C–H wagging)

~1150

Only one band (1420–1330 cm–1), position depending on the degree of hydrogen bonding

α-Unsaturation decrease >C–O stretch by 30 cm–1; liquid spectra of alcohols show a broad out-of-plane bending band (769–650, s)


Organic Oxygen Compounds


General Formula

>C=O Stretch

Aldehydes

R–CHO

Saturated, aliphatic

R = alkyl

1720–1720 (s)

Aryl

R = aryl

1705–1695 (s)

~2820 (m), ~2720 (m) Fermi resonance between C–H stretch and first overtone of the aldehydic C–H bending

α,β-Unsaturated

>C=C–CHO

1700–1680 (s)

α,β,γ,δ-Unsaturated

>C=C–C=C–CHO

1680–1660 (s)

β-Ketoaldehyde

–C(=O)C–CHO

1670–1645 (s) (lowering is possible due to intramolecular hydrogen bonding in enol form)

α-Halo-

>C X


–C(=O)H Stretch

CHO X=halogen

~1740 (s)

~2900 (m), ~2750 (m) (aromatic)

Notes


Organic Oxygen Compounds (continued)


General Formula

>C=O Stretch

>C–O Stretch

Amides

Notes See Organic Nitrogen Compounds

Anhydrides

>C(=O)O(=O)C
C(=O)O(=O)C
C–O Stretch

–O–H Stretch

–O–H Bend

R–COOH

~1760 (s)

~1420

3550 (s)

~1250 (m/s)

Ar–COOH

1730–1710 1720–1706 (s)

~1400 1315–1280 (m) (sometimes doublet)

3500 (s) 3300–2500 (s, broad)

~1250 (m/s) 900–860 (m, broad) (out-of-plane)

1700–1680 (s)

1315–1280 (m) (sometimes doublet)

3300–2500 (s, broad)

900–860 (m, broad) (out-of-plane)

O

H ..,, O C

R

O

O

H ... O C

R

R

C

O...H R = alkyl Dimer, α,βunsaturated (or aromatic)

>C=O Stretch

C

O...H O R = alkenyl


R

Notes

700–610 (s) 1370–1220 (w) (overtone)



Family

General Formula –

Salt

R–COO

Cyanates

R–C≡N→O

Epoxides

Wavenumbers (cm–1) >C=O Stretch

See Organic Nitrogen Compounds ~1250 (s) (ring breathing, sym) 950–810 (s) (asym) 840–810 (s) (C–H bend) 3050-2990 (m/s) (C–H stretch)

R1 C

C O

R2

Esters

R1–COOR2

Saturated, aliphatic

R1,R2 = alkyl

1750–1735 (s) α-Halogen substitution results in an increase in wavenumbers (up to 30 cm–1)

1210–1163 (s) [acetates only: 1240 (s)]

Formates

R1 = H, R2 = alkyl

1730–1715 (s)

~1180 (s), ~1160 (s)


Notes

1610–1550 (s) asym CO2– ~1400 (s) sym CO2–

R1 R2

>C–O Stretch

(O–C–C) 1046–1031 (s) (1° alcohol) ~1100 (s) (2° alcohol)



>C=C–COOR2 R2 = alkyl

1730–1715 (s)

1300–1250 (s) 1200–1050 (s)

Benzoate

C6H5–COOR2 R2 = alkyl

1730–1715 (s)

1310–1250 (s) 1180–1100 (s)

Vinyl

R1–COOCH=CH2 R1 = alkyl

1775–1755 (s)

1300–1250 (s) ~1210 (vs)

Phenyl

R1–COOC6H5 R1 = alkyl

~1770 (s)

1300–1200 (s) 1190–1140 (s)

α-Ketoesters

–C(=O)COOR2 R2 = alkyl

1775–1740 (s)

1300–1050 (s) (two peaks)

β-Ketoesters

–C(=O)-C–C(=O)R2

~1735 (s) ~1650 (s) (due to enolization) –C=C–C–OR2  \\ O–H …O

1300–1050 (s) (two peaks)

~1735 (s)

1300–1050 (s) (two peaks)

R2 = alkyl

Aryl benzoates


R1–COOR2 R1, R2 = aryl

1573_C08.fm Page 389 Tuesday, November 25, 2003 3:30 PM

α,β-Unsaturated

Family

General Formula 1

2

Wavenumbers (cm–1) >C–O–C< Stretch >C–O–C< Stretch Asymmetrical Symmetrical

Notes

Ethers Aliphatic

R –O–R R1,R2 = alkyl

1150–1085 (s) (branching off on the carbons adjacent to oxygen creates splitting)

Very hard to trace

Aryl alkyl

R1 = alkyl R2 = aryl

1275–1200 (s) (high due to resonance)

1075–1020 (s)

Vinyl

R1 = vinyl R2 = aryl

1225–1200 (s) (high due to resonance)

1075–1020 (s)

Imides

(R–C=O)2NH

See Organic Nitrogen Compounds

Isocyanates

R–N=C=O


Ketals

OR3 R1

C

R2

1190–1160 1195–1125 1098–1063 1055–1035

1660–1610 (m) (>C=CC) ~1000 (m), 909 (m) (>C=C–H) (wagging)

(s) (s) (s) (s)

OR4 Ketenes


>C=C=O

~2150 (s) (>C=C=O)



Family

Wavenumbers (cm–1) >C=O Stretch >C=C< Stretch

General Formula

Ketones

R1C(=O)R2

Aliphatic, saturated

R1, R2 = alkyl

1720–1710 (s)

α,β-Unsaturated

>C=C–C(=O)R2 R2 = alkyl

~1690 (s) (s-cis) ~1675 (s) (s-trans)

1650–1600 (m)

α,β-α1,β1Unsaturated

(>C=C–)2C=O

~1665 (s)

~1640 (m)

α,β,γ,δUnsaturated

>C=C–C=C–C(=O)R2 R2 = alkyl

~1665 (s)

~1640 (m)

Aryl

R1 = aryl R2 = alkyl

~1690 (s)

~1600, 1500 (m/s) (aromatic)

Diaryl

R1, R2 = aryl

~1665 (s)

~1600, 1500 (m/s) (aromatic)

Cyclic C

O

Notes >C=O overtone ~3400 (w); solid samples or solutions decrease >C=O stretch (10–20 cm–1) α-Halogenation increases >C=O stretch (0–25 cm–1) >C–H stretch is very weak (3100–2900 cm–1)

Three-membered: 1850 (s) Four-membered: 1780 (s) Five-membered: 1745 (s) Six-membered: 1715 (s) Larger than six-membered: 1705 (s)

α-Keto (s-trans)

R1–C(=O)COR2

~1720 (s) (aliphatic) ~1680 (s) (aromatic)

β-Keto

R1COCH2COR2

~1720 (s) (two bands)

1640–1580 (m, broad) Due to enol from R1

C O

CH

C

Shows a shallow broad –OH band (enol form) at 3000–2700 cm–1

R2

H ........... O

α-Amino ketone hydrochlorides

+ R1COCH2NH3 Cl–

>C=O decreases 10–15 cm–1 with electron deactivating p-substituents

α-Amino ketones

R–COCH2NR2

Strong bands at 3700–3600 cm–1 (–OH) and 1700–1600 cm–1 (>C=O) due to the presence of enolic forms




Family

General Formula

>C=O Stretch


>C–O stretch

Lactams (cyclic amides)

Notes See Organic Nitrogen Compounds

Lactones (cyclic esters) (CH2)x

O Saturated αγβ-

x=4

~1735 (s)

1300–1050 (s, two peaks)

x=3 x=2

~1770 (s) ~1840 (s)

1300–1050 (s, two peaks) 1300–1050 (s, two peaks)

Unsaturated, α- to the carbonyl (>C=O)

x=4 x=3

~1720 (s) ~1750 (s) (doublet 1785–1755 cm–1 when α-hydrogen present)


Unsaturated, α- to the oxygen

x=4 x=3

~1760 (s) ~1790 (s)

~1685 (s) ~1660 (s)


Unsaturated, α- to the carbonyl and α- to the oxygen

x = 4 (α-pyrone, coumarin)

1775–1715 (s, doublet)

1650–1620 (s) 1570–1540 (s)

1300–1050 (s, two peaks)

Nitramines

R1 >N–NO2


R2 Nitrates

R–NO3


Nitro compounds

R–NO2


Nitrosamines

R1


>N–N=O R2 N-Nitroso compounds


R1–N–N=O  R2


1573_C08.fm Page 392 Tuesday, November 25, 2003 4:04 PM


Family

General Formula 1

2

Peroxides

R –O–O–R

Aliphatic

R1, R2 = alkyl 1

2

>C–O Stretch

Wavenumbers (cm–1) –O–H Stretch >C=O Stretch

–C–C–O–

Notes

–C(=O)O

890–820 (vw)

Aromatic

R , R = aromatic

~1000 (vw)

Acyl, aliphatic

R1, R2 = acyl (aliphatic)

890–820 (vw)

1820–1810 (s) 1800–1780 (s)

Acyl, aromatic

R1, R2 = acyl (aromatic)

~1000 (vw)

1805–1780 (s) 1785–1755 (s)

Peroxyacids

R1–C(=O)OOH

~1260 (s)

Peroxyacids, anhydride Alkyl Aryl

(R1–COO)2 R1 = alkyl R1 = aryl

(–COO–OOC–) 1815 (s), 1790 (s) 1790 (s), 1770 (s)


–O–H Bend

3300–3250 (s, not as broad as in R–COOH)

1745–1735 (s) (doublet)

~1400 (m)

~850 cm–1 (m, –O–O– stretch)




General Formula

Phenols

Ar–OH Ar = aryl

Phosphates

(R1O)3P=O

Phosphinates

1

>C–O Stretch ~1230 (m)

–O–H Stretch

–O–H Bend

~3610 (m, sharp) (in CHCl3 or CCl4 solution) ~3100 (m, broad) (in neat samples)

1410–1310 (m, broad) (in-plane) ~650 (m) (out-of-plane)

Notes

See Organic Phosphorus Compounds

(R O)P(=O)H2


Phosphine oxides

R3P=O


Phosphonates

(R1O)2P(=O)H


Phosphorus acids

R2P(=O)OH


Pyrophosphates

(R–P=O)2O





Family Quinones 1,21,4Silicon compounds

General Formula

Wavenumbers (cm–1) >C=O Stretch >C=C< Stretch ~1675 (s) ~1675 (s)

Notes

~1600 (s) ~1600 (s) See Organic Silicon Compounds

Sulfates

See Organic Sulfur Compounds

Sulfonamides


Sulfonates


Sulfones


Sulfonyl chlorides


Sulfoxides





Family

General Formula

Others

Notes

Amides Primary

R1–CONH2

1400 (s) (stretch)

3520 (m) (stretch) 3400 (m) (stretch) 1655–1620 (m) (bend) 860–666 (m, broad) (wagging)

>C=O (1650) (s, solid state) (1690) (s, solution)

Lowering of N–H stretch occurs in solid samples due to hydrogen bonding; higher values arise in dilute samples

Secondary

R1–CONHR2

1400 (s) (stretch)

3500–3400 (w) (stretch) 1570–1515 (w) (bend) 860–666 (m, broad) (wagging)

>C=O (1700–1670) (s, solution); (1680–1630) (s, solid state) Band due to interaction of N–H (bend) and (C–N) (stretch) (~1250) (m, broad)

Lowering of N–H stretch occurs in solid samples due to hydrogen bonding; higher values arise in dilute samples

Tertiary

R1–CONR2R3

1400 (s) (stretch)

—

>C=O (1680–1630) (s); higher values are obtained with electron attracting groups attached to the nitrogen

R1–NH2

1250–1020 (m) (for nonconjugated amines) 1342–1266 (s) (for aromatic amines)

3500 (w) (stretch) 3400 (w) (stretch) 1650–1580 (m) (scissoring) 909–666 (m) (wagging)

Secondary

R1–NHR2


3350–3310 (w) (stretch) 1515 (vw) (scissoring) 909–666 (m) (wagging)

Tertiary

R1–NR2R3


Amine salts Primary

RNH3+X–

Amines Primary


C–N

Wavenumbers (cm–1) N–H

—

3000–2800 (s) 2800–2200 (m) (series of peaks) 1600–1575 (m) 1550–1504 (m)


Organic Nitrogen Compounds

R2NH2+X–

3000–2700 (s) 2700–2250 (m) (series of peaks) 2000 (w) 1620–1560 (m)

Tertiary

R3NH+X–

2700–2250 (s)

Quaternary Amino acids (alpha)

+

R 4N X

R1

–

— 3100–2600 (s, broad) 2222–2000 (s, broad, overtone) 1610 (w) (bend) 1550–1485 (s) (bend)

COO−

CH NH2

R1


Secondary

–COO– (1600–1590) (s) –COOH (1755–1730) (s)

COO−

CH +NH3

R1

CH

COOH

+NH3 Ammonium ion

NH4+

Azides

R–N3

Azocompounds

R1–N=N–R2 (trans)

Azoxy compounds

R–N=N→O


3300–3040 (s) 2000–1709 (m) 1429 (s) 2140 (s) (asym stretch, N3) 1295 (s) (sym stretch, N3) Forbidden in IR but allowed in Raman spectrum (1576) (w); peak is lowered to 1429 cm–1 in unsymmetrical p-electron-donating substituted azobenzenes 1310–1250 (s)

Family Cyano compounds (nitriles)

Wavenumbers (cm–1) C–N Multiple Bond Cumulated (–X=C=Y) Double Bond

General Formula R–C≡N

Diazonium salts

Electronegative elements αto the C≡N group reduce the intensity of the absorption

2260–2240 (w) (aliphatic) 2240–2220 (m) (aromatic, conjugated)

R–N≡N

2280–2240 (m) (–N∫N) +

+

Imides R

C

NH

O Isocyanates

R–N=C=O

Isocyanides (isonitriles)

R–N≡C

C

1710,1700 (>C=O sixmembered ring) 1770,1700 (>C=O fivemembered ring)

R

O 2273–2000 (s) (broad) (asym) 1400–1350 (w) (sym) 2400–2300 (w) (aliphatic) 2300–2200 (w) (aromatic)

Isonitriles

See Isocyanides

Isothiocyanates

R–N=C=S

2140–2000 (s) (stretch)

Ketene

R1

2150 (stretch); 1120 >C=C=O

R2 Ketenimine

R1

2000 (stretch) >C=C=N–

R2


Notes


Organic Nitrogen Compounds (continued)

Family

General Formula

>C–N

Wavenumbers (cm–1) >N–O >N–O (Asymmetric) (Symmetric)

Lactams C

O

N

H

(CH2)n

Nitramines R1

Others

Notes

>C=O (s) (stretch) 1670 (six-membered ring) 1700 (five-membered ring) 1745 (four-membered ring) N–H (out-of-plane wagging) (800–700) (broad)

Add ~15 cm–1 to every wavenumber in case of a >C=C< in conjugation; amide group is forced into the cis-conformation in rings of medium size

1620–1580 (s) (asym) 1320–1290 (s) (sym) N

NO2

R2 Nitrates

RO–NO2

Nitriles (cyano compounds)

R–C≡N

Nitrites

RO–N=O

Nitro compounds Aliphatic

R–NO2 R–alkyl

870

1615–1540 (vs) (asym) 1390–1320 (vs) (sym)

1390–1320 (vs)

Aromatic

R=aryl

(Difficult to assign)

1548–1508 (s) (asym) 1356–1340 (s) (sym)

1356–1340 (s)

Nitrosamines

R1 >N–N=O R2


–N=O 1660–1625 (s) (asym) 1300–1225 (s) (asym) >N–O 870–833 (s) (stretch) 763–690 (s) (bend) See Cyano compounds –N=O stretch 1680–1650 (vs) (trans) 1625–1610 (vs) (cis) >N–O stretch 850–750 (vs) ~610 (m) (CNO bend)

>N–O stretch (1520–1500) (s) (vapor) (1500–1480) (s) (neat) N–N (1150–925) (m)

Aromatics absorb at lower frequencies than aliphatic



Family

General Formula

N-Nitroso compounds

R–N=O

Pyridines

Sulfilimines

C5H5N

R1 S=N–R3

>C–N

Wavenumbers (cm–1) >N–O >N–O (Asymmetric) (Symmetric)

Others

Notes

N=O stretch 1585–1539 (s) (3°, aliphatic) 1511–1495 (s) (3°, aromatic)

1 and 2°C — nitroso compounds are unstable and rearrange or dimerize

N–H (3075, 3030) (s) C–H (out-of-plane) (920–720) (s) (2000–1650) (overtone) C=C ring stretch (1600, 1570, 1500, 1435)

Characteristic substitution pattern: α-Substitution: (795–780), (755–745) β-Substitution: (920–880), (840–770), 720 See Organic Sulfur Compounds

R2 Sulfonamides

R–SO2NH2


Thiocyanates

R–SC≡N





General Formula

Family 1

Disulfides

R –S–S–R

Mercaptans

R–S–H

>S=O (Asymmetric)

Wavenumbers (cm–1) >S=O (Symmetric) >S=N–

2

Others

Notes

–S–S– (S→O) (for sulfoxides)

Reduction of all >S=O frequencies due to H– bonding with –NH

R2(O=)CNH | RSCH2CH | HOOC

1295–1280 (s) (for sulfones)

1135–1100 (s) (for sulfones)

Sulfates

(RO)2S(=O)2

1415–1380 (s)

1200–1185 (s)

Sulfides

R1–S–R2

Sulfilimines N-Acyl N-Alkyl N-Sulfonyl

R2S=N–R1 R2S=N–COR1 R2S=N–R1 R2S=N–SO2R1

Sulfinamides, N-alkylidene

RS(O)N=CR2

Sulfonamides

R–SO2NH2

1370–1335 (s)

1170–1155 (s)

Sulfonates

R1–SO2–OR2

1372–1335 (s)

1195–1168 (s)

Electron-donating groups on the aryl group cause higher-frequency absorption

Sulfones

R1–SO2–R2

1350–1300 (s)

1160–1120 (s)

Hydrogen bonding reduces the frequency of absorption slightly

Sulfonic acids (anhydrous)

R–SO3H

1350–1342 (s)

1165–1150 (s)

Sulfonic acids, salts

R–SO3–

ca. 1175 (s)

ca. 1055 (s)

Mercapturic acids


R–S– (700–600) (w)

1280–1200 (s) 1095–1030 (s)

1160–1135 (s)

800 (s) 987–935 (s) 980–901 (s)

>C=O (1625–1600) (s)

1520 (amide II band) 1080 (s, S→O) >N–H (1°) (3390–3330) (s) (3300–3247) (s) >N–H (2°) (3265) (s)

–OH (3300–2500) (s, broad)

Solid phase spectra lower wavenumbers by 10–20 cm–1

Hydrated sulfonic acids show broad bands at 1230–1150 cm–1


Organic Sulfur Compounds

Family

General Formula

>S=O (Asymmetric)

Others

Notes

Hydrogen bonding reduces the frequency absorption slightly; electronegative substituents increase the >S→O frequency; inorganic complexation reduces the >S→O (up to 50 cm–1)

Sulfonyl chlorides

R–SO2Cl

Sulfoxides Cyclic

R2S→O (CH2)x S→O

>S→O (1070–1030) (s) x=3 1192 (CCl4) 1073 (CHCl3) x=4 1035 (CCl4) 1020 (CHCl3) x=5 1053 (CCl4) 1031 (CHCl3)

Thiocarbonyls (not trimerized into cyclic sulfides)

R1–C–R2(H) || S

>C=S (1250–1020) (s)

Thiocyanates

R–S–C≡N

–C≡N (2175–2140) (s); higher values for aryl thiocyanates

Thiol esters

R1–C–SR2 || O

>C=O (1690) (s) (S-alkyl thioester) (1710) (s) (S-aryl thioester)

Thiols

R–SH

Thiophenols

Ar–SH


1410–1380 (s)

Wavenumbers (cm–1) >S=O (Symmetric) >S=N– 1204–1177 (s)

The (+) mesomeric effect of sulfur is larger than its (–) inductive effect

See Mercaptans –S–H (2600–2500) (w)


Organic Sulfur Compounds (continued)


General Formula

Silanes Monoalkyl Dialkyl Trialkyl

RxSiHy R–SiH3 R2SiH2 R3SiH

Tetraalkyl Alkoxy

R4Si Rx1Si(OR2)y

Siloxanes Disiloxanes Cyclic trimer Cyclic tetramer

>Si–O–Si< | |

Hydroxysilanes

RxSi(OH)y


>Si–H Stretch

>Si–H Bend

>C–Si< Stretch

2130–2100 (s) ~2135 (s) 2360–2150 (s)

890–860 (s) 890–860 (s) 890–860 (s)

890–690 820–800 ~840 (s) ~755 (s) 890–690 890–690

>C–H Bend

(s) (s)

~1260 (s) (rocking) ~1260 (s) (rocking) ~1260 (s) (rocking)

(s) (s)

~1260 (s) (rocking) ~1260 (s) (rocking)

>Si–O– Stretch

–OH Stretch

1090–1080 (s) (doublet) 1110–1000 (s) (Si–O–Si) ~1053 (s) ~1020 (s) ~1082 (s) ~3680 (s) (confirmed by band at 870–820 cm–1)


Organic Silicon Compounds

Family

General Formula

>P=O Stretch

Wavenumbers (cm–1) >P–H Stretch >P–O–C< Stretch

Phosphates Alkyl Aryl

O=P(OR)3

1300–1100 (s) (doublet) 1285–1260 (s) (doublet) 1315–1290 (s) (doublet)

Phosphinates

H2P–OR || O

1220–1180 (s)

~2380 (m) ~2340 (m) (sharp)

Phosphine oxides Alkyl Aryl

(R)H–PR1R2 || O

1185–1150 (s) 1145–1095 (s)

2340–2280 (m) 2340–2280 (m)

Phosphates

H–P(OR)2 || O

1265–1230 (s)

2450–2420 (m)

Phosphorus acids

R1P(=O)OH | R2

1240–1180 (vs)

Phosphorus amides

(RO)2PNR1R2 || O

1275–1200 (s)

Pyrophosphates

R2P–O–PR2 || || O O

1310–1200 (s) (single band)


–OH Stretch

~1050 (s) (alkyl) 950–875 (s) (aryl)

Notes –>P=O stretch can shift up to 65 cm–1 due to solvent effect

~1050 (s) (alkyl) 950–875 (s) (aryl) –>P=O decreases with complexation ~1050 (s) (alkyl) 950–875 (s) (aryl) 2700–2200 (s, broad) (assoc)


Organic Phosphorus Compounds


General Formula

Fluorides

X=F

Chlorides

>CX2 Stretch

–CH3 Stretch

1120–1010

1350–1200 (asym) 1200–1080 (sym)

1350–1200 (asym) 1200–1080 (sym)

X = Cl

830–500 1510–1480 (overtone)

845–795 (asym) ~620 (sym)

Bromides

X = Br

667–290

Iodides

X=I

500–200


>C–X Stretch

=C–X Stretch 1230–1100


I

Organic Halogen Compounds


COMMON SPURIOUS INFRARED ABSORPTION BANDS The following table provides some of the common potential sources of spurious infrared absorptions that might appear on a spectrum. Common Spurious Infrared Absorption Bands Approximate Wavenumber (in cm–1)

Wavelength µm) (µ

Compound or Group

3700 3650 3450 2900 2350 2330 2300 and 2150

2.70 2.74 2.9 3.44 4.26 4.30 4.35 and 4.65

H 2O H 2O H 2O –CH3, >CH2 CO2 CO2 CS2

5.01 5–7 5.52 5.7

BO2– H 2O CI2CO Phthalic anhydride >C=O Phthalates H 2O CO2 CO3–2 NO3– ->SiO– ->Si–O–Si<SO4–2 (CH2O)x ->C–Cl NO3– KNO3 CCl4 vapor CCl4 liquid

1996 1400–2000 1820 1755 1700–1760 1720 1640 1520 1430 1360 1270 1000–1110 980 935 907 837 823 794 788 720 and 730 728 667 Any

5.7–5.9 5.8 6.1 6.6 7.0 7.38 7.9 9–10 10.2 10.7 11.02 11.95 12.15 12.6 12.7 13.7 and 13.9 13.75 14.98 Any


Polyethylene ->Si–F CO3–2 Fringes

Origin Water in solvent (thick layers) Water in some quartz windows Hydrogen-bonded water, usually in KBr disks Paraffin oil, residual from previous mulls Atmospheric absorption, or dissolved gas from a dry ice bath Leaky cells, previous analysis of samples dissolved in carbon disulfide Metaborate in the halide window Atmospheric absorption Phosgene, decomposition product in purified CHCl3 Decomposition product of phthalate esters or resins; paint off-gas product Bottle-cap liners leached by sample Phthalate polymer plastic tubing Water of crystallization entrenched in sample Leaky cells, previous analysis Contaminant in halide window Contaminant in halide window Silicone oil or grease Glass; silicones From decomposition of sulfates in KBr pellets Deposit from gaseous formaldehyde Dissolved R-12 (Freon-12) Contaminant in halide window From decomposition of nitrates in KBr pellets Leaky cells, from CCl4 used as a solvent Incomplete drying of cell or contamination, from CCl4 used as a solvent Various experimental sources SiF4, found in NaCl windows Atmospheric carbon dioxide If refractive index of windows is too high, or if the cell is partially empty, or the solid sample is not fully pulverized


CHAPTER

9

Nuclear Magnetic Resonance Spectroscopy

CONTENTS Properties of Important NMR Nuclei Gyromagnetic Ratio of Some Important Nuclei Classification of Important Quadrupolar Nuclei According to Natural Abundance and Magnetic Strength Chemical Shift Ranges of Some Nuclei Reference Standards for Selected Nuclei 1H and 13C Chemical Shifts of Useful Solvents for NMR Measurements Proton NMR Absorption of Major Chemical Families Organic Nitrogen Compounds Some Useful 1H Coupling Constants Additivity Rules in 13C NMR Correlation Tables 13C NMR Absorptions of Major Functional Groups 13C NMR Chemical Shifts of Organic Families 15N Chemical Shifts for Common Standards 15N Chemical Shifts of Major Chemical Families Spin–Spin Coupling to 15N 19F Chemical Shift Ranges 19F Chemical Shifts of Some Fluorine-Containing Compounds Fluorine Coupling Constants Residual Peaks Observed in the 1H NMR Spectra of Common Deuterated Organic Solvents



PROPERTIES OF IMPORTANT NMR NUCLEI The following table lists the magnetic properties required most often for choosing the nuclei to be used in NMR experiments.1–14 Refer to several excellent texts and the literature for guidelines in nucleus selection.

REFERENCES 1. Silverstein, R.M., Bassler, G.C., and Morrill, T.C., Spectrometric Identification of Organic Compounds, 5th ed., John Wiley & Sons, New York, 1991. 2. Yoder, C.H. and Shaeffer, C.D., Introduction to Multinuclear NMR, Benjamin/Cummings, Menlo Park, CA, 1987. 3. Gordon, A.J. and Ford, R.A., The Chemist’s Companion, Wiley Interscience, New York, 1971. 4. Silverstein, R.M. and Webster F.X., Spectrometric Identification of Organic Compounds, 6th ed., John Wiley & Sons, New York, 1998. 5. Becker, E.D., High Resolution NMR, Theory and Chemical Applications, 2nd ed., Academic Press, New York, 1980. 6. Gunther, H., NMR Spectroscopy: Basic Principles, Concepts and Applications in Chemistry, John Wiley & Sons, New York, 2003. 7. Rahman, A.-U., Nuclear Magnetic Resonance, Springer-Verlag, New York, 1986. 8. Harris, R.K., NMR and the periodic table, Chem. Soc. Rev., 5, 1, 1976. 9. Kitamaru, R., Nuclear Magnetic Resonance: Principles and Theory, Elsevier Science, Amsterdam, 1990. 10. Lambert, J.B., Holland, L.N., and Mazzola, E.P., Nuclear Magnetic Resonance Spectroscopy: Introduction to Principles, Applications and Experimental Methods, Prentice Hall, Englewood Cliffs, NJ, 2003. 11. Bovey, F.A. and Mirau, P.A., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., Academic Press, New York, 1988. 12. Harris, R.K. and Mann, B.E., NMR and the Periodic Table, Academic Press, London, 1978. 13. Hore, P.J. and Hore, P.J., Nuclear Magnetic Resonance, Oxford University Press, Oxford, 1995. 14. Nelson, J.H., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., John Wiley & Sons, New York, 2003.



Properties of Important NMR Nuclei

Isotope H1 2 1H 3b 1H 13 C 6 14 7N 15 N 7 17 8O 19 F 9 29 14Si 31 P 15 33 16S 35 b S 16 35 17Cl 36 b Cl 17 76 b 35Br 79 Br 35 81 35Br 183 W 74 1

Natural Abundance 99.985 0.015 — 1.108 99.635 0.365 0.037 100 4.70 100 0.76 — 75.53 — — 50.54 49.46 14.40

Spin Number I

10.000

1/2 1 1/2 1/2 1 1/2 5/2 1/2 1/2 1/2 3/2 3/2 3/2 2 1 3/2 3/2 1/2

42.5759 6.53566 45.4129 10.7054 3.0756 4.3142 5.772 40.0541 8.4578 17.235 3.2654 5.08 4.1717 4.8931 4.18 10.667 11.498 1.7716

NMR Frequencya at Indicated Field Strength in kG 14.092 21.139 23.487 51.567 60.0000 9.21037 63.9980 15.0866 4.3343 6.0798 8.134 42.3537 11.9191 24.288 4.6018 7.16 5.8790 6.8956 5.89 15.032 16.204 2.4966

90.0000 13.81555 95.9971 22.6298 6.5014 9.1197 12.201 63.5305 17.8787 36.433 6.9026 10.74 8.8184 10.3434 8.84 22.549 24.305 3.7449

100.0000 15.35061 106.6634 25.1443 7.2238 10.1330 13.557 94.0769 19.8652 40.481 7.6696 11.932 9.7983 11.4927 9.82 25.054 27.006 4.1610

220.0000 33.77134 234.6595 55.3174 15.924 22.2925 29.825 206.9692 43.7035 89.057 16.8731 26.250 21.5562 25.2838 21.60 55.119 59.413 9.1543

Electric Quadrupole Momentc (barns) — 0.0028 — — 0.01 — −0.026 — — — −0.055 0.04 −0.079 −0.017 ±0.25 0.31 0.26 —

Isotope

Field Valuea (kg) at Frequency of 4 MHz 10 MHz 16 MHz

Relative Sensitivity Constant H Constant ν

Magnetic Moment (eh/4πMc)

H1 H2 3b 1H 13 6C 14 N 7 15 7N 17 O 8 19 9F 29 14Si 31 15P 33 16S 35 b 16S 35 Cl 17 36 b 17Cl 76 b Br 35 79 35Br 81 Br 35 183 74W

0.940 6.120 0.881 3.736 13.01 9.272 6.93 0.999 4.729 2.321 12.25 7.87 9.588 0.175 9.6 3.750 3.479 22.58

1.00 9.65 × 10−3 1.21 0.0159 1.01 × 10−3 1.04 × 10−3 0.0291 0.834 7.84 × 10−3 0.0665 2.26 × 10−3 8.50 × 10−3 4.72 × 10−3 0.0122 2.52 × 10−3 0.0794 0.0994 7.3 × 10−5

2.79278 0.85742 2.9789 0.7024 0.4036 −0.2831 −1.8937 2.6288 −0.55477 1.1317 0.6533 1.00 0.82183 1.285 ±0.548 2.106 2.270 0.117

1 1

a b c

2.349 15.30 2.202 9.341 32.51 23.18 17.3 2.497 11.82 5.802 30.62 19.7 23.97 20.44 24 9.375 8.697 56.45

3.758 24.48 3.523 14.946 52.02 37.09 27.7 3.994 18.92 9.284 49.0 31.5 38.35 32.70 38 15.00 13.92 90.31

1 kG = 10−10 T, the corresponding SI unit. Nucleus is radioactive. 1 b = 10−23 m2.


1.00 0.409 1.07 0.252 0.193 0.101 1.58 0.941 0.199 0.405 0.384 0.597 0.490 0.920 0.26 1.26 1.35 0.042


GYROMAGNETIC RATIO OF SOME IMPORTANT NUCLEI The following table lists the gyromagnetic ratio, γ, of some important nuclei that are probed in NMR spectroscopy.1–12 The gyromagnetic ratio is the proportionality constant that correlates the magnetic moment (µ) and the angular momentum, ρ: µ = γρ.

REFERENCES 1. Carrington, A. and McLaughlin, A., Introduction to Magnetic Resonance, Harper and Row, New York, 1967. 2. Levine, I.M., Molecular Spectroscopy, John Wiley & Sons, New York, 1975. 3. Becker, E.D., High Resolution NMR: Theory and Chemical Applications, Academic Press, New York, 1980. 4. Yoder, C.H. and Shaeffer, C.D., Introduction to Multinuclear NMR, Benjamin/Cummings, Menlo Park, CA, 1987. 5. Silverstein, R.M. and Webster F.X., Spectrometric Identification of Organic Compounds, 6th ed., John Wiley & Sons, New York, 1998. 6. Rahman, A.-U., Nuclear Magnetic Resonance, Springer-Verlag, New York, 1986. 7. Kitamaru, R., Nuclear Magnetic Resonance: Principles and Theory, Elsevier Science, Amsterdam, 1990. 8. Lambert, J.B., Holland, L.N., and Mazzola, E.P., Nuclear Magnetic Resonance Spectroscopy: Introduction to Principles, Applications and Experimental Methods, Prentice Hall, Englewood Cliffs, NJ, 2003. 9. Bovey, F.A. and Mirau, P.A., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., Academic Press, 1988. 10. Hore, P.J. and Hore, P.J., Nuclear Magnetic Resonance, Oxford University Press, Oxford, 1995. 11. Nelson, J.H., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., John Wiley & Sons, New York, 2003. 12. Gunther, H., NMR Spectroscopy: Basic Principles, Concepts and Applications in Chemistry, John Wiley & Sons, New York, 2003. Gyromagnetic Ratio of Some Important Nuclei Nucleus H1 H2 3 1H 7 3Li 10 B 5 11 5B 13 C 6 14 7N 15 N 7 17 8O 19 F 9 29 14Si 23 Na 11 31 15P 33 16S 35 17Cl 37 Cl 17 39 19K 79 35Br 81 35Br 183 W 74 1 1


γ 5.5856 0.8574 5.9575 2.1707 0.6002 1.7920 1.4044 0.4035 −0.5660 −0.7572 5.2545 −1.1095 1.4774 2.2610 0.4284 0.5473 0.4555 0.2607 1.3993 1.5084 0.2324


CLASSIFICATION OF IMPORTANT QUADRUPOLAR NUCLEI ACCORDING TO NATURAL ABUNDANCE AND MAGNETIC STRENGTH The following table classifies important quadrupolar nuclei according to their natural abundance and relative magnetic strength.1 The magnetic strength, while not a commonly recognized physical parameter, is defined as a matter of convenience for classification of nuclei in NMR. It is defined as follows: Strong γ/107 > 2.5 rad T−1sec−1 Medium 10 rad T−1sec−1 > γ107 > 2.5 rad T−1sec−1 Weak γ107 < 2.5 rad T−1sec−1

where the flux density in units of tesla (T) and rad refers to 2π. In NMR, one can write: 2πf = γB where f is the resonant frequency, γ is the gyromagnetic ratio, and B is the flux density. Thus, for the proton, γ/2π = 43 MHz/T, resulting in a value of γ/107 = 4.3 rad B−1sec−1, and therefore medium magnetic strength. The less favorable nuclei for a given element are listed in brackets.

REFERENCES 1. Harris, R.K. and Mass, B.E., NMR and the Periodic Table, Academic Press, London, 1978. Classification of Important Quadrupolar Nuclei According to Natural Abundance and Magnetic Strength Magnetic Strength

Natural Abundance Medium

>90%) High (>

Strong

7

Li

Medium

9

Be, 23Na, 27Al, 45Sc, 51V, 55Mn, 59Co, 75As, 93Nb, 115In, 127I, 133Cs, 181Ta, 209Bi

Weak

14

N,

39

K

[10B], 11B, 35Cl, 63Cu, 65Cu, [69Ga], 71Ga, [79Br], 81Br, [85Rb], 87Rb, 121Sb, [123Sb], 137Ba, 139La, [185Re], 187Re

2

25

33

Mg, 37Cl, 83Kr, Os, 201Hg

189


CH–C=C< ~2.5 ppm >C=C–H 4.2–6.2 ppm

CH3–C–C=C< ~1.0 ppm –CH2–C–C=C< ~1.4 ppm >CH–C–C=C< ~1.8 ppm

Alkynes

CH3–C≡C– ~1.7 ppm –CH2–C≡C– ~2.2 ppm >CH–C≡C– ~2.7 ppm R–C≡C–H ~2.4 ppm

CH3–C–C≡C– ~1.2 ppm >CH2–C–C≡C– ~1.5 ppm >CH–C–C≡C– ~1.8 ppm

Aromatics

C6H5–G

Range: 8.5–6.9 ppm

G op

m-

When G=electron withdrawing (e.g., >C=O, –NO2, –C≡N), oand p-hydrogens relative to –G are closer to 8.5 ppm (more downfield)


When G=electron donating (e.g., –NH2, –OH, –OR, –R), o- and phydrogens relative to –G are closer to 6.9 ppm (more upfield)


Organic Oxygen Compounds Approximate δ of Protons Underlined or Indicated

Family Alcohols

CH3–OH 3.2 ppm RCH2–OH 3.4 ppm R2CH–OH 3.6 ppm CH3–C–OH 1.2 ppm RCH2–C–OH 1.5 ppm R2CH–C–OH 1.8 ppm R–O–H (1–5 ppm — depending on concentration)

Aldehydes

CH3–CHO 2.2 ppm CH3–C–CHO 1.1 ppm

Amides


Anhydrides, acyclic

CH3–C(=O)O– 1.8 ppm CH3–C–C(=O)O– 1.2 ppm

Anhydrides, cyclic

3.0 ppm

RCH2–CHO 2.4 ppm RCH2–C–CHO 1.6 ppm

R2CH–CHO 2.5 ppm

RCH2–C(=O)O– 2.1 ppm RCH2–C–C(=O)O– 1.8 ppm

R2CH–C(=O)O– 2.3 ppm R2CH–C–C(=O)O– 2.0 ppm 7.1 ppm

O

O

CH2

C

CH

C O

O CH2

CH

C O

Carboxylic acids

CH3–COOH 2.1 ppm CH3–C–COOH 1.1 ppm

Cyclic ethers

Oxacyclopropane (oxirane)

O

RCH2–COOH 2.3 ppm R–CH2–C–COOH 1.6 ppm R–COO–H 11–12 ppm

2.5 ppm

Oxacyclobutane (oxetane)

R2CH–COOH 2.5 ppm R2CH–C–COOH 2.0 ppm

O

2.7 ppm

O 4.7 ppm

Oxacyclopentane (tetrahydrofuran)

1.9 ppm

3.8 ppm O

Oxacyclohexane (tetrahydropyran)

1.6 ppm 1.6 ppm

O


C

3.6 ppm


Organic Oxygen Compounds (continued) Approximate δ of Protons Underlined or Indicated

Family 1,4-Dioxane

O

3.6 ppm

O

1,3-Dioxane 1.7 ppm

O 4.7 ppm

3.8 ppm

O

Furan 6.3 ppm

7.4 ppm O

Dihydropyran 1.9 ppm 4.5 ppm

6.2 ppm O

Epoxides Esters

See Cyclic Ethers CH3–COOR R = alkyl 1.9 ppm R = aryl 2.0 ppm

RCH2–COOR 2.1 ppm 2.2 ppm

R2CH–COOR 2.3 ppm 2.4 ppm

CH3–C–COOR 1.1 ppm CH3–OOC–R 3.6 ppm CH3–C–OOC–R 1.3 ppm

RCH2–C–COOR 1.7 ppm RCH2–OOC–R 4.1 ppm RCH2–C–OOC–R 1.6 ppm

R2CH–C–COOR 1.9 ppm R2CH–OOC–R 4.8 ppm R2CH–C–OOC-R 1.8 ppm

Cyclic 2.1 ppm

4.4 ppm

1.6 ppm 1.6 ppm

2.3 ppm

4.1 ppm

O O

2.3 ppm O O

Ethers R = alkyl R = aryl

CH3–O–R 3.2 ppm 3.9 ppm

RCH2–O–R 3.4 ppm 4.1 ppm

R2CH–O–R 3.6 ppm 4.5 ppm

R = alkyl R = aryl

CH3–C–O–R 1.2 ppm 1.3 ppm

RCH2–C–O–R 1.5 ppm 1.6 ppm

R2CH–C–O–R 1.8 ppm 2.0 ppm



Organic Oxygen Compounds (continued) Approximate δ of Protons Underlined

Family Isocyanates

See Nitrogen Compounds

Ketones

CH3–C(=O)– 1.9 ppm R = alkyl 2.4 ppm R = aryl

(CH2)n

RCH2–C(=O)– 2.1 ppm 2.7 ppm

R2CH–C(=O)– 2.3 ppm 3.4 ppm

CH3–C(=O)– RCH2–C(=O)– 1.1 ppm R = alkyl 1.6 ppm 1.2 ppm R = aryl 1.6 ppm Cyclic ketones (n = number of ring carbons)

R2CH–C(=O)– 2.0 ppm 2.1 ppm

O α-hydrogens 2.0–2.3 ppm (n > 5) 3.0 ppm (n = 4) 1.7 ppm (n = 3) β-hydrogens 1.9–1.5 ppm

Lactones

See Esters, Cyclic

Nitro compounds


Phenols

Ar–O–H 9–10 ppm (Ar = aryl)



ORGANIC NITROGEN COMPOUNDS Amides δ of Proton(s) (Underlined)

Primary R–C(=O)NH2 δ, ppm

Secondary R–C(=O)NHR1 δ, ppm

Tertiary R–C(=O)NR1R2 δ, ppm

5–12

5–12

—

— — —

~2.9 ~3.4 ~3.8

~2.9 ~3.4 ~3.8

~1.1 ~1.5 ~1.9

~1.1 ~1.5 ~1.9

~1.1 ~1.5 ~1.9

~1.9 ~2.1 ~2.2

~2.0 ~2.1 ~2.2

~2.1 ~2.1 ~2.2

~1.1 ~1.5 ~1.8

~1.1 ~1.5 ~1.8

~1.1 ~1.5 ~1.8

1. N-substitution R–C(=O)N–H a. Alpha –C(=O)N–CH3 –C(=O)N–CH2– –C(=O)N–CH– b. Beta –C(=O)N–C–CH3 –C(=O)N–C–CH2– –C(=O)N–C–CH– 2. C-substitution a. Alpha CH3–C(=O)N RCH2–C(=O)N R2CH–C(=O)N b. Beta CH3–C–C(=O)N CH2–C–C(=O)N CH–C–C(=O)N Amines δ of Proton(s) (Underlined) 1. Alpha protons >N–CH3 >N–CH2– >N–CH< 2. Beta protons >N–C–CH3 >N–C–CH2– >N–C–CH
CH–C≡N ~2.9

2. Beta hydrogens δ, ppm CH3–C–C≡N ~1.2 –CH2–C–C≡N ~1.6 >CH–C–C≡N ~2.0

Imides 1. Alpha hydrogens δ, ppm CH3–C(=O)NHC(=O)– ~2.0 CH2–C(=O)NHC(=O)– ~2.1 CH–C(=O)NHC(=O)– ~2.2

2. Beta hydrogens δ, ppm CH3–C(=O)C–NH–C(=O)– ~1.2 CH2–C(=O)C–NH–C(=O)– ~1.3 CH–C(=O)C–NH–C(=O)– ~1.4

Isocyanates Alpha hydrogens δ, ppm CH3–N=C=O ~3.0 –CH2–N=C=O ~3.3 >CH–N=C=O ~3.6



Isocyanides (Isonitriles)

Isothiocyanates

Alpha hydrogens δ, ppm CH3–N=C< ~2.9 CH2–N=C< ~3.3 CH–N=C< ~4.9

Alpha hydrogens δ, ppm CH3–N=C=S ~3.4 CH2–N=C=S ~3.7 CH–N=C=S ~4.0

Nitriles δ, ppm –CH2–O–N=O

~4.8

Nitro Compounds δ, ppm CH3–NO2 ~ 4.1 CH3–C–NO2 ~1.6


–CH2–NO2 –CH2–C–NO2

~4.2 ~2.1

–CH–NO2 ~4.4 –CH–C–NO2 ~2.5


Organic Sulfur Compounds δ of Proton(s) Underlined

Family Benzothiopyrans 2H–1– 4H–1– 2,3,4H–1– Disulfides

Isothiocyanates

Mercaptans (thiols)

S-methyl salts Sulfates Sulfides

Sulfilimines Sulfonamides Sulfonates Sulfones Sulfonic acids Sulfoxides Thiocyanates

Thiols

3

sp C–H ~3.3 ppm sp3 C–H ~3.2 ppm sp3 C–H 1.9–2.8 ppm

sp2 C–H 5.8–6.4 aromatic ~6.8 sp2 C–H 5.9–6.3 aromatic ~6.9 aromatic ~7.1

CH3–S–S–R ~2.4 ppm CH2–S–S–R ~2.7 ppm CH–S–S–R ~3.0 ppm CH3–N=C=S ~2.4 ppm –CH2–N=C=S ~2.7 ppm >CH–N=C=S ~3.0 ppm CH3–S–H ~2.1 ppm –CH2–S–H ~2.6 ppm >CH–S–H ~3.1 ppm + >S–CH3 ~3.2 pm (CH3–O)2S(=O)2 ~3.4 ppm CH3–S– 1.8–2.1 ppm R–CH2–S– 1.9–2.4 ppm R–CHR–S– 2.8–3.4 ppm Ar–CH2–S– 4.1–4.2 ppm Ar–CHR–S– 3.6–4.2 ppm Ar2–CH–S– 5.1–5.2 ppm

CH3–C–S–S–R ~1.2 ppm CH2–C–S–S–R ~1.6 ppm CH–C–S–S–R ~2.0 ppm

CH3(R)S=N–R2 CH3–SO2NH2 CH3–SO2–OR CH3–SO2–R2 CH3–SO3H CH3–S(=O)R –CH2–S(=O)R CH3–S–C≡N –CH2–S–C≡N –CH–S–C≡N See Mercaptans

Note: Ar represents aryl.


~2.5 ppm ~3.0 ppm ~3.0 ppm ~2.6 ppm ~3.0 ppm ~2.5 ppm ~3.1 ppm ~2.7 ppm ~3.0 ppm ~3.3 ppm

CH3–C–S–H ~1.3 ppm –CH2–C–S–H ~1.6 ppm >CH–C–S–H ~1.7 ppm

CH3–CH2–S– 1.1–1.2 ppm CH3–CHR–S– 0.8–1.2 ppm CH3–CHAr–S– 1.3–1.4 ppm CH3–CR2–S– 1.0 ppm Ar–CH2–CHR–S– 3.0–3.2 ppm >C=C–CH2–CHAr–S– 2.4–2.6 ppm >C=C–CH2–CAr2–S– 2.5 ppm R2CH–CH2–S– 2.6–3.0 ppm Ar2 CH–CH2–S– 4.0–4.2 ppm >C=C–CHR–CHAr–S– 2.3–2.4 ppm >C=C–CHR–CAr2–S– 2.8–3.2 ppm


SOME USEFUL 1H COUPLING CONSTANTS This section gives the values of some useful proton NMR coupling constants (in Hz). The data are adapted with permission from the work of Dr. C.F. Hammer, Professor Emeritus, Chemistry Department, Georgetown University, Washington, D.C. 20057. The single numbers indicate a typical average, while in some cases the range is provided. 1. Freely rotating chains. H

7 6−8

C

H (−) 12−15

C
C

H

OH

≈0

3. Alkenes 10

H

H

+1.5 to 2.5

9−13

C

C

C

H (−)

0−3 C

H

17

10

H H

C

12−18

C

1−2

H

H

>C

C< C

C H

C

3−11 7

6−12

4. Alkynes

5. Aldehydes

1−2

H >C

1−2

(−) C

H C

H

>C

C

C

H

H

C

C

2−3

8

H C

H

6−10 8

H

1−3

H 0 −1 (−)


O

H

5−8

C O

6. Aromatic

H

C C


ADDITIVITY RULES IN

13

C NMR CORRELATION TABLES

The wide chemical shift range (~250 ppm) of 13C NMR is responsible for the considerable change of a chemical shift noted when a slight inductive, mesomeric, or hybridization neighboring change occurs. Following the various empirical correlations in 1H NMR,1–7 D.W. Brown8 has developed a short set of 13C NMR correlation tables. This section covers a part of those as adopted by Yoder and Schaeffer9 and Clerk et al.10 Refer to reference 8 for some accurate data on more complicated structures and look up the various references included in the literature cited below.1–17

REFERENCES 1. Shoolery, J.N., Varian Associates Technical Information Bulletin, Vol. 2, No. 3, Palo Alto, CA, 1959. 2. Bell, H.M., Bowles, D.B., and Senese, F., Additive NMR chemical shift parameters for deshielded methine protons, Org. Magn. Reson., 16, 285, 1981. 3. Matter, U.E., Pascual, C., Pretsch, E., Pross, A., Simon, W., and Sternhell, S., Estimation of the chemical shifts of olefinic protons using additive increments. II. Compilation of additive increments for 43 functional groups, Tetrahedron, 25, 691, 1969. 4. Matter, U.E., Pascual, C., Pretsch, E., Pross, A., Simon, W., and Sternhell, S., Estimation of the chemical shifts of olefinic protons using additive increments. III. Examples of utility in N.M.R. studies and the identification of some structural features responsible for deviations from additivity, Tetrahedron, 25, 2023, 1969. 5. Jeffreys, J.A.D., A rapid method for estimating NMR shifts for protons attached to carbon, J. Chem. Educ., 56, 806, 1979. 6. Mikolajczyk, M., Grzeijszczak, S., and Zatorski, A., Organosulfur compounds IX: NMR and structural assignments in α,β-unsaturated sulphoxides using additive increments method, Tetrahedron, 32, 969, 1976. 7. Friedrich, E.C. and Runkle, K.G., Empirical NMR chemical shift correlations for methyl and methylene protons, J. Chem. Educ., 61, 830, 1984. 8. Brown, D.W., A short set of 13C-NMR correlation tables, J. Chem. Educ., 62, 209, 1985. 9. Yoder, C.H. and Schaeffer, C.D., Jr., Introduction to Multinuclear NMR, Benjamin/Cummings Publishing Co., Menlo Park, CA, 1987. 10. Clerk, J.T., Pretsch, E., and Seibl, J., Structural Analysis of Organic Compounds by Combined Application of Spectroscopic Methods, Elsevier, Amsterdam, 1981. 11. Silverstein, R.M. and Webster F.X., Spectrometric Identification of Organic Compounds, 6th ed., John Wiley & Sons, New York, 1998. 12. Gunther, H., NMR Spectroscopy: Basic Principles, Concepts and Applications in Chemistry, John Wiley & Sons, New York, 2003. 13. Kitamaru, R., Nuclear Magnetic Resonance: Principles and Theory, Elsevier Science, Amsterdam, 1990. 14. Lambert, J.B., Holland, L.N., and Mazzola, E.P., Nuclear Magnetic Resonance Spectroscopy: Introduction to Principles, Applications and Experimental Methods, Prentice Hall, Englewood Cliffs, NJ, 2003. 15. Bovey, F.A. and Mirau, P.A., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., Academic Press, New York, 1988. 16. Harris, R.K. and Mann, B.E., NMR and the Periodic Table, Academic Press, London, 1978. 17. Nelson, J.H., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., John Wiley & Sons, New York, 2003.



Alkanes The chemical shift (in ppm) of Ci can be calculated from the following empirical equation: ∆i = −2.3 + Σ Ai where Σ Ai is the sum of increments allowed for various substituents depending on their positions (α, β, γ, δ) relative to the 13C in question and (−2.3) is the chemical shift for methane relative to tetramethylsilane (TMS). 13

C Chemical Shift Increments for A, the Shielding Term for Alkanes and Substituted Alkanes9,10 Increments Substituent >C– (sp3) >C=C< (sp2) –C≡C– (sp) C 6H 5 –F –Cl –Br –I –OH –OR –CHO –COR –COOH –COO– –COCl –COOR –OOCR –N< –NH3+ [ >N< ]+ –ONO –NO2 –CON< –NHCO– –C≡N –NC –S– –S–CO– –SO– –SO2Cl –SCN –C(=S)N– –C=NOH(syn) –C=NOH(anti) R1R2R3Sn R1, R2, and R3 = organic substituents


α

β

γ

δ

9.1 19.5 4.4 22.1 70.1 31.0 18.9 –7.2 49.0 49.0 29.9 22.5 20.1 24.5 33.1 22.6 5.5 28.3 26.0 30.7 54.3 61.6 22.0 31.3 3.1 31.5 10.6 17.0 31.1 54.5 23.0 33.1 11.7 16.1 –5.2

9.4 6.9 5.6 9.3 7.8 10.0 11.0 10.9 10.1 10.1 −0.6 3.0 2.0 3.5 2.3 2.0 6.5 11.3 7.5 5.4 6.1 3.1 2.6 8.3 2.4 7.6 11.4 6.5 9.0 3.4 9.7 7.7 0.6 4.3 4.0

−2.5 −2.1 −3.4 −2.6 −6.8 −5.1 −3.8 −1.5 −6.2 −6.2 −2.7 −3.0 −2.8 −2.5 −3.6 −2.8 −6.0 −5.1 −4.6 −7.2 −6.5 −4.6 −3.2 −5.7 −3.3 −3.0 −3.6 −3.1 −3.5 −3.0 −3.0 −2.5 −1.8 −1.5 −0.3

0.3 0.4 −0.6 0.3 0.0 −0.5 −0.7 −0.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.0 −1.4 −0.5 −1.0 −0.4 0.0 −0.5 0.0 −0.4 0.0 0.0 0.0 0.0 0.6 0.0 0.0 0.0


Thus, the 13C shift for Ci in 2-pentanol is predicted to be β α i α′ β′ CH3–CH2–CH2–CH(OH)–CH3 δi = (–2.3) + [9.1 + 9.4 + 9.1 + 9.4 + 10.1] = 44.8 ppm α β α′ β′ OH Alkenes For a simple olefin of the type –Cγ–Cβ–Cα–Ci = C–Cα′–Cβ′–Cγ ′– δi = 122.8 + Σ Ai where Aα = 10.6, Aβ = 7.2, Aγ = –1.5, Aα′ = –7.9, Aβ′ = –1.8, Aγ′ = 1.5, and 122.8 is the chemical shift of the sp2 carbon in ethene. If the olefin is in the cis configuration, an increment of –1.1 ppm must be added. Thus, the 13C shift for C-3 in cis-3-hexene is predicted to be β α i α′ β′ CH3–CH2–CH = CH–CH2–CH3 δi = 122.8 + [10.6 + 7.2 – 1.5 – 7.9] + (–1.1) = 130.1 ppm (α) (β) (α′) (β′) (cis) Alkynes For a simple alkyne of the type –Cα–Cβ–Ci ≡ C–Cα′–Cβ′– δi = 71.9 + ΣAi where increments A are given in the table below and 71.9 is the chemical shift of the sp carbon in acetylene.9 13

C Chemical Shift Increments for A, the Shielding Term for Alkynes Increments

Substituents C (sp3) –CH3 –CH2CH3 –CH(CH3)2 –CH2OH –COCH3 –C6H5 –CH=CH2 –Cl

α

β

6.9 7.0 12.0 16.0 11.1 31.4 12.7 10.0 −12.0

4.8

α′ −5.7 −5.7 −3.5 −3.5 1.9 4.0 6.4 11.0 −15.0

Thus, the 13C shift for C–1 in 1-phenyl propyne is predicted to be C6H5 – C1i ≡ C2–CH3 1

2

δi = 71.9 + 7.0 + 6.4 = 85.3 ppm Copyright © 2003 CRC Press, LLC

β′ 2.3


while the 13C shift for C–2 in the same compound is predicted to be C6H5–C1 ≡ C2i–CH3 1

2

δi = 71.9 + 6.9 + 6.4 = 85.20 ppm

Benzenoid Aromatics For a benzene derivative, C6H5–X, where X = substituent, δi = 128.5 + Σ Ai where Σ Ai is the sum of increments given below and 128.5 is the chemical shift of benzene.9,10

13

C Chemical Shift Increments for A, the Shielding Term for Benzenoid Aromatics X–C6H5, where X = Substituent Substituent X –CH3 –CH2CH3 –CH(CH3)2 –C(CH3)3 –CH=CH2 –C≡CH –C6H5 –CHO –COCH3 –CO2H –CO2– –CO2R –CONH2 –CN –Cl –OH –O– –OCH3 –OC6H5 –OC(=O)CH3 –NH2 –NHCH3 –N(CH3)2 –NO2 –SH –SCH3 –SO3H

Ci 9.3 15.89, 15.710 20.39, 20.110 22.49, 22.110 7.6 –6.1 13.0 8.69, 9.010 9.19, 9.310 2.19, 2.410 7.6 2.1 5.4 –15.49, –16.010 6.29, 6.410 26.9 39.610 31.49, 30.210 29.1 23.0 18.79, 19.210 21.710 22.4 20.09, 19.610 2.2 9.910 15.0

Increments ortho meta 9

10

0.8 , 0.6 –0.49, –0.610 –1.99, –2.010 –3.19, –3.410 –1.8 3.8 –1.1 1.39, 1.210 0.19, 0.210 1.59, 1.610 0.8 1.2 –0.3 3.69, 3.510 0.49, 0.210 –12.7 –8.210 –14.49, –14.710 –9.5 –6.4 –12.4 –16.210 –15.7 –4.89, –5.310 0.7 –2.010 –2.2

0.0 –0.1 0.19, 0.010 –0.29, 0.410 –1.8 0.4 0.5 0.69, 1.210 0.09, 0.210 0.09, –0.110 0.0 0.0 –0.9 0.69, 0.710 1.39, 10.010 1.4 1.910 1.09, 0.910 0.3 1.3 1.3 0.710 0.8 0.99, 0.810 0.4 0.110 1.3

para –2.99, –3.110 –2.69, –2.810 –2.49, –2.510 –2.99, –3.110 –3.5 –0.2 –1.0 5.59, 6.010 4.2 5.19, 4.810 2.8 4.4 5.0 3.99, 4.310 –1.99, –2.010 –7.3 –13.610 –7.79, –8.110 –5.3 –2.3 –9.5 –11.810 –11.8 5.89, 6.010 –3.1 –3.710 3.8

As an example, the 13C shift for the benzene carbon (C i) carrying the carbonyl in 3,5-dinitroacetophenone, CH3C(=O)(C6H3)(NO2)2, is predicted to be Ci = 128.5 + 9.1 + 2(0.9) = 132.4 ppm



13

C NMR ABSORPTIONS OF MAJOR FUNCTIONAL GROUPS

The table below lists the 13C chemical shift ranges (in ppm) with the corresponding functional groups in descending order. A number of typical simple compounds for every family is given to illustrate the corresponding range. The shifts for the carbons of interest are given in parentheses for each carbon as it appears either from left to right in the formula or by the underscore.1–14

REFERENCES 1. Yoder, C.H. and Schaeffer, C.D., Jr., Introduction to Multinuclear NMR: Theory and Application, Benjamin/Cummings Publishing Co., Menlo Park, CA, 1987. 2. Brown, D.W., A short set of 13C-NMR correlation tables, J. Chem. Ed., 62, 209, 1985. 3. Silverstein, R.M. and Webster, F.X., Spectrometric Identification of Organic Compounds, 6th ed., John Wiley & Sons, New York, 1998. 4. Becker, E.D., High Resolution NMR, Theory and Chemical Applications, 2nd ed., Academic Press, New York, 1980. 5. Gunther, H., NMR Spectroscopy: Basic Principles, Concepts and Applications in Chemistry, Wiley, New York, 2003. 6. Kitamaru, R., Nuclear Magnetic Resonance: Principles and Theory, Elsevier Science, Amsterdam, 1990. 7. Lambert, J.B., Holland, L.N., and Mazzola, E.P., Nuclear Magnetic Resonance Spectroscopy: Introduction to Principles, Applications and Experimental Methods, Prentice Hall, Englewood Cliffs, NJ, 2003. 8. Bovey, F.A. and Mirau, P.A., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., Academic Press, New York, 1988. 9. Harris, R.K. and Mann, B.E., NMR and the Periodic Table, Academic Press, London, 1978. 10. Hore, P.J., Nuclear Magnetic Resonance, Oxford University Press, Oxford, 1995. 11. Nelson, J.H., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., Wiley, New York, 2003. 12. Levy, G.C., Lichter, R.L., and Nelson, G.L., Carbon-13 Nuclear Magnetic Resonance Spectroscopy, 2nd ed., Wiley, New York, 1980. 13. Pihlaja, K. and Kleinpeter, E., Carbon-13 NMR Chemical Shifts in Structural and Stereochemical Analysis, VCH, New York, 1994. 14. Aldrich Library of 1H and 13C FT-NMR Spectra, Aldrich Chemical Company, Milwaukee, 1996.



13

δ (ppm) 220–165

C NMR Absorptions of Major Functional Groups Group >C=O

Family Ketones Aldehydes α,β-Unsaturated carbonyls Carboxylic acids Amides Esters

140–120

>C=C
CH–

Sulfides (thioethers) Alkanes, cycloalkanes

Example (δδ of Underlined Carbon) (CH3)2CO (CH3)2CHCOCH3 CH3CHO CH3CH=CHCHO CH2=CHCOCH3 HCO2H CH3CO2H HCONH2 CH3CONH2 CH3CO2CH2CH3 CH2=CHCO2CH3 C 6H 6 CH2=CH2 CH2=CHCH3 CH2=CHCH2Cl CH3CH=CHCH2CH3 CH3–C≡N HC≡CH CH3C≡CCH3 CH3OOCCH2CH3 HOCH3 HOCH2CH3 CH3NH2 CH3CH2NH2 C6H5–S–CH3 CH4 CH3CH3 CH3CH2CH3 CH3CH2CH2CH3 CH3CH2CH2CH2CH3 Cyclohexane


(206.0) (212.1) (199.7) (192.4) (169.9) (166.0) (178.1) (165.0) (172.7) (170.3) (165.5) (128.5) (123.2) (115.9, 136.2) (117.5, 133.7) (132.7) (117.7) (71.9) (73.9) (57.6, 67.9) (49.0) (57.0) (26.9) (35.9) 15.6 (–2.3) (5.7) (15.8, 16.3) (13.4, 25.2) (13.9, 22.8, 34.7) (26.9)


13

C NMR CHEMICAL SHIFTS OF ORGANIC FAMILIES

The following bibliography should give a good set of references for the various organic families. This collection is by no means complete and should be updated regularly.

REFERENCES Adamantanes Maciel, G.E., Dorn, H.C., Greene, R.L., Kleschick, W.A., Peterson, M.R., Jr., and Wahl, G.H., Jr., 13C chemical shifts of monosubstituted adamantanes, Org. Magn. Reson., 6, 178, 1974.

Amides Jones, R.G. and Wilkins, J.M., Carbon-13 NMR spectra of a series of parasubstituted N,N-dimethylbenzamides, Org. Magn. Reson., 11, 20, 1978.

Benzazoles Sohr, P., Manyai, G., Hideg, K., Hankovszky, H., and Lex, L., Benzazoles. XIII. Determination of the E and Z configuration of isomeric 2-(2-benzimidazolyl)-di- and tetra-hydrothiophenes by IR, 1H and 13C NMR spectroscopy, Org. Magn. Reson., 14, 125, 1980.

Carbazoles Giraud, J. and Marzin, C., Comparative 13C NMR study of deuterated and undeuterated dibenzothiophenes, dibenzofurans, carbazoles, fluorenes, and fluorenones, Org. Magn. Reson., 12, 647, 1979.

Chlorinated Compounds Hawkes, G.E., Smith, R.A., and Roberts, J.D., Nuclear magnetic resonance spectroscopy: carbon-13 chemical shifts of chlorinated organic compounds, J. Org. Chem., 39, 1276, 1974. Mark, V. and Weil, E.D., The isomerization and chlorination of decachlorobi-2,4-cyclopentadien-1-yl, J. Org. Chem., 36, 676, 1971.

Diazoles and Diazines Faure, R., Vincent, E.J., Assef, G., Kister, J., and Metzger, J., Carbon-13 NMR study of substituent effects in the 1,3-diazole and -diazine series, Org. Magn. Reson., 9, 688, 1977.

Disulfides Bass, S.W. and Evans, S.A., Jr., Carbon-13 nuclear magnetic resonance spectral properties of alkyl disulfides, thiosulfinates, and thiosulfonates, J. Org. Chem., 45, 710, 1980. Freeman, F. and Angeletakis, C.N., Carbon-13 nuclear magnetic resonance study of the conformations of disulfides and their oxide derivatives, J. Org. Chem., 47, 4194, 1982. Takata, T., Iida, K., and Oae, S., 13C-NMR chemical shifts and coupling constants JC-H of six membered ring systems containing sulfur-sulfur linkage, Heterocytes, 15, 847, 1981.



Fluorenes and Fluorenones Giraud, J. and Marzin, C., Comparative 13C NMR study of deuterated and undeuterated dibenzothiophenes, dibenzofurans, carbazoles, fluorenes and fluorenones, Org. Magn. Reson., 12, 647, 1979.

Furans Giraud, H. and Marzin, C., Comparative 13C NMR study of deuterated and undeuterated dibenzothiophenes, dibenzofurans, carbazoles, fluorenes and fluorenones, Org. Magn. Reson., 12, 647, 1979.

Imines Allen, M. and Roberts, J.D., Effects of protonation and hydrogen bonding on carbon-13 chemical shifts of compounds containing the >C=N-group, Can. J. Chem., 59, 451, 1981.

Oxathianes Murray, W.T., Kelly, J.W., and Evans, S.A., Jr., Synthesis of substituted 1,4-oxathianes, mechanistic details of diethoxytriphenylphosphorane — and triphenylphosphine/tetra-chloromethane — promoted cyclodehydrations and 13C NMR spectroscopy, J. Org. Chem., 52, 525, 1987. Szarek, W.A., Vyas, D.M., Sepulchre, A.M., Gero, S.D., and Lukacs, G., Carbon-13 nuclear magnetic resonance spectra of 1,4-oxathiane derivatives, Can. J. Chem., 52, 2041, 1974.

Oximes Allen, M. and Roberts, J.D., Effects of protonation and hydrogen bonding on carbon-13 chemical shifts of compounds containing the >C=N-group, Can. J. Chem., 59, 451, 1981.

Polynuclear Aromatics (Naphthalenes, Anthracenes, Pyrenes) Adcock, W., Aurangzeb, M., Kitching, W., Smith, N., and Doddzell, D., Substituent effects of carbon-13 nuclear magnetic resonance: concerning the π-inductive effect, Aust. J. Chem., 27, 1817, 1974. DuVernet, R. and Boekelheide, V., Nuclear magnetic resonance spectroscopy: ring-current effects on carbon13 chemical shifts, Proc. Natl. Acad. Sci. U.S.A., 71, 2961, 1974.

Pyrazoles Puar, M.S., Rovnyak, G.C., Cohen, A.I., Toeplitz, B., and Gougoutas, J.Z., Orientation of the sulfoxide bond as a stereochemical probe: synthesis and 1H and 13C NMR of substituted thiopyrano[4,3-c]pyrazoles, J. Org. Chem., 44, 2513, 1979.

Sulfides Chauhan, M.S., and Still, I.W.J., 13C nuclear magnetic resonance spectra of organic sulfur compounds: cyclic sulfides, sulfoxides, sulfones, and thiones, Can. J. Chem., 53, 2880, 1975. Gokel, G.W., Gerdes, H.M., and Dishong, D.M., Sulfur heterocycles. 3. Heterogenous, phase-transfer, and acid catalyzed potassium permanganate oxidation of sulfides to sulfones and a survey of their carbon13 nuclear magnetic resonance spectra, J. Org. Chem., 45, 3634, 1980. Mohraz, M., Jiam-qi, W., Heilbronner, E., Solladie-Cavallo, A., and Matloubi-Moghadam, F., Some comments on the conformation of methyl phenyl sulfides, sulfoxides, and sulfones, Helv. Chim. Acta, 64, 97, 1981.



Srinivasan, C., Perumal, S., Arumugam, N., and Murugan, R., Linear free-energy relationship in naphthalene system-substituent effects on carbon-13 chemical shifts of substituted naphthylmethyl sulfides, Ind. J. Chem., 25A, 227, 1986.

Sulfites Buchanan, G.W., Cousineau, C.M.E., and Mundell, T.C., Trimethylene sulfite conformations: effects of sterically demanding substituents at C-4,6 on ring geometry as assessed by 1H and 13C nuclear magnetic resonance, Can. J. Chem., 56, 2019, 1978.

Sulfonamides Chang, C., Floss, H.G., and Peck, G.E., Carbon-13 magnetic resonance spectroscopy of drugs: sulfonamides, J. Med. Chem., 18, 505, 1975.

Sulfones (See Also Other Families for the Corresponding Sulfones) Balaji, T. and Reddy, D.B., Carbon-13 nuclear magnetic resonance spectra of some new arylcycfloproyl sulphones, Ind. J. Chem., 18B, 454, 1979. Fawcett, A.H., Ivin, K.J., and Stewart, C.D., Carbon-13 NMR spectra of monosulphones and disulphones: substitution rules and conformational effects, Org. Magn. Reson., 11, 360, 1978. Gokel, G.W., Gerdes, H.M., and Dishong, D.M., Sulfur heterocycles. 3. Heterogeneous, phase-transfer, and acid catalyzed potassium permanganate oxidation of sulfides to sulfones and a survey of their carbon13 nuclear magnetic resonance spectra, J. Org. Chem., 45, 3634, 1980.

Sulfoxides (See Also Other Families for the Corresponding Sulfoxides) Gatti, G., Levi, A., Lucchini, V., Modena, G., and Scorrano, G., Site of protonation in sulphoxides: carbon13 nuclear magnetic resonance evidence, J. Chem. Soc. Chem. Commun., 251, 1973. Harrison, C.R. and Hodge, P., Determination of the configuration of some penicillin S-oxides by 13C nuclear magnetic resonance spectroscopy, J. Chem. Soc. Perkin Trans., I, 1772, 1976.

Sulfur Ylides Matsuyama, H., Minato, H., and Kobayashi, M., Electrophilic sulfides (II) as a novel catalyst. V. Structure, nucleophilicity, and steric compression of stabilized sulfur ylides as observed by 13C-NMR spectroscopy, Bull. Chem. Soc. Jpn., 50, 3393, 1977.

Thianes Barbarella, G., Dembech, P., Garbesi, A., and Fara, A., 13C NMR of organosulfur compounds. II. 13C chemical shifts and conformational analysis of methyl substituted thiacyclohexanes, Org. Magn. Reson., 8, 469, 1976. Block, E., Bazzi, A.A., Lambert, J.B., Wharry, S.M., Andersen, K.K., Dittmer, D.C., Patwardhan, B.H., and Smith, J.H., Carbon-13 and oxygen-17 nuclear magnetic resonance studies of organosulfur compounds: the four-membered-ring-sulfone effect, J. Org. Chem., 45, 4807, 1980. Murray, W.T., Kelly, J.W., and Evans, S.A., Jr., Synthesis of substituted 1,4-oxathianes: mechanistic details of diethoxytriphenyl phosphorane and triphenylphosphine/tetrachloromethane — promoted cyclodehydrations and 13C NMR spectroscopy, J. Org. Chem., 52, 525, 1987. Rooney, R.P., and Evans, S.A., Jr., Carbon-13 nuclear magnetic resonance spectra of trans-1-thiadecalin, trans1,4-dithiadecalin, trans-1,4-oxathiadecalin, and the corresponding sulfoxides and sulfones, J. Org. Chem., 45, 180, 1980. Willer, R.L. and Eliel, E.L., Conformational analysis. 34. Carbon-13 nuclear magnetic resonance spectra of saturated heterocycles. 6. Methylthianes, J. Am. Chem. Soc., 99, 1925, 1977.



Thiazines Fronza, G., Mondelli, R., Scapini, G., Ronsisvalle, G., and Vittorio, F., 13C NMR of N-heterocycles: conformation of phenothiazines and 2,3-diazaphenothiazines, J. Magn. Reson., 23, 437, 1976.

Thiazoles Chang, G., Floss, H.G., and Peck, G.E., Carbon-13 magnetic resonance spectroscopy of drugs: sulfonamides, J. Med. Chem., 18, 505, 1975. Elguero, J., Faure, R., Lazaro, R., and Vincent, E.J., 13C NMR study of benzothiazole and its nitroderivatives, Bull. Soc. Chim. Belg., 86, 95, 1977. Faure, R., Galy, J.P., Vincent, E.J., and Elguero, J., Study of polyheteroaromatic pentagonal heterocycles by carbon-13 NMR: thiazoles and thiazolo[2,3-e]tetrazoles, Can. J. Chem., 56, 46, 1978. Harrison, C.R. and Hodge, P., Determination of the configuration of some penicillin S-oxides by 13C nuclear magnetic resonance spectroscopy, J. Chem. Soc. Perkin Trans., I, 1772, 1976.

Thiochromanones Chauhan, M.S. and Still, I.W.J., 13C nuclear magnetic resonance spectra of organic sulfur compounds: cyclic sulfides, sulfoxides, sulfones and thiones, Can. J. Chem., 53, 2880, 1975.

Thiones Chauhan, M.S. and Still, I.W.J., 13C nuclear magnetic resonance spectra of organic sulfur compounds: cyclic sulfides, sulfoxides, sulfones and thiones, Can. J. Chem., 53, 2880, 1975.

Thiophenes Balkau, F., Fuller, M.W., and Heffernan, M.L., Deceptive simplicity in ABMX N.M.R. spectra. I. Dibenzothiophen and 9.9′-dicarbazyl, Aust. J. Chem., 24, 2293, 1971. Benassi, R., Folli, U., Iarossi, D., Schenetti, L., and Tadei, F., Conformational analysis of organic carbonyl compounds. Part 3. A 1H and 13C nuclear magnetic resonance study of formyl and acetyl derivatives of benzo[b]thiophen, J. Chem. Soc. Perkin Trans., II, 911, 1983. Clark, P.D., Ewing, D.F., and Scrowston, R.M., NMR studies of sulfur heterocycles: III. 13C spectra of benzo[b]thiophene and the methylbenzo[b]thiophenes, Org. Magn. Reson., 8, 252, 1976. Fujieda, K., Takahashi, K., and Sone, T., The C-13 NMR spectra of thiophenes. II. 2-Substituted thiophenes, Bull. Chem. Soc. Jpn., 58, 1587, 1985. Geneste, P., Olive, J.L., Ung, S.N., El Faghi, M.E.A., Easton, J.W., Beierbeck, H., and Saunders, J.K., Carbon13 nuclear magnetic resonance study of benzo[b]thiophenes and benzo[b]thiophene S-oxides and S,Sdioxides, J. Org. Chem., 44, 2887, 1979. Giraud, J. and Marzin, C., Comparative 13C NMR study of deuterated and undeuterated dibenzothiophenes, dibenzofurans, carbazoles, fluorenes and fluorenones, Org. Magn. Reson., 12, 647, 1979. Kiezel, L., Liszka, M., and Rutkowski, M., Carbon-13 magnetic resonance spectra of benzothiophene and dibenzothiophene, Spec. Lett., 12, 45, 1979. Osamura, Y., Sayanagi, O., and Nishimoto, K., C-13 NMR chemical shifts and charge densities of substituted thiophenes: the effect of vacant dπ orbitals, Bull. Chem. Soc. Jpn., 49, 845, 1976. Perjessy, A., Janda, M., and Boykin, D.W., Transmission of substituent effects in thiophenes: infrared and carbon-13 nuclear magnetic resonance studies, J. Org. Chem., 45, 1366, 1980. Satonaka, H. and Watanabe, M., NMR spectra of 2-(2-nitrovinyl) thiophenes, Bull. Chem. Soc. Jpn., 58, 3651, 1985. Stuart, J.G., Quast, M.J., Martin, G.E., Lynch, V.M., Simmonsen, H., Lee, M.L., Castle, R.N., Dallas, J.L., John B.K., and Johnson, L.R.F., Benzannelated analogs of phenanthro [1,2-b]-[2,1-b]thiophene: synthesis and structural characterization by two-dimensional NMR and x-ray techniques, J. Heterocyclic Chem., 23, 1215, 1986.



Thiopyrans Senda, Y., Kasahara, A., Izumi, T., and Takeda, T., Carbon-13 NMR spectra of 4-chromanone, 4H-1-benzothiopyran-4-one, 4H-1-benzothiopyran-4-one 1,1-dioxide, and their substituted homologs, Bull. Chem. Soc. Jpn., 50, 2789, 1977.

Thiosulfinates and Thiosulfonates Bass, S.W. and Evans, S.A., Jr., Carbon-13 nuclear magnetic resonance spectral properties of alkyl disulfides, thiosulfinates, and thiosulfonates, J. Org. Chem., 45, 710, 1980.



15

N CHEMICAL SHIFTS FOR COMMON STANDARDS

The following table lists the 15N chemical shifts (in ppm) for common standards. The estimated precision is better than 0.1 ppm. Nitromethane, according to Levy and Lichter,1 is the most suitable primary measurement reference, but has the disadvantage of lying in the low-field end of the spectrum. Thus, ammonia (which lies in the most upfield region) is the most suitable for routine experimental use.1–6

REFERENCES 1. Levy, G.C. and Lichter, R.L., Nitrogen-15 Nuclear Magnetic Resonance Spectroscopy, John Wiley & Sons, New York, 1979. 2. Lambert, J.B., Shurvell, H.F., Verbit, L., Cooks, R.G., and Stout, G.H., Organic Structural Analysis, MacMillan, New York, 1976. 3. Witanowski, M., Stefaniak, L., Szymanski, S., and Januszewski, H., External neat nitromethane scale for nitrogen chemical shifts, J. Magn. Reson., 28, 217, 1977. 4. Srinivasan, P.R. and Lichter, R.L., Nitrogen-15 nuclear magnetic resonance spectroscopy: evaluation of chemical shift references, J. Magn. Reson., 28, 227, 1977. 5. Briggs, J.M. and Randall, E.W., Nitrogen-15 chemical shifts in concentrated aqueous solutions of ammonium salts, Mol. Phys., 26, 699, 1973. 6. Becker, E.D., Proposed scale for nitrogen chemical shifts, J. Magn. Reson., 4, 142, 1971. 15

N Chemical Shifts for Common Standards

Compound

Formula

Ammonia

NH3

Ammonium nitrate

NH4NO3

Ammonium chloride

NH4Cl

Tetraethylammonium chloride

(C2H5)4N+Cl–

Tetramethyl urea Dimethylformamide (DMF) Nitric acid (aqueous solution)

[(CH3)2N]2CO (CH3)2NCHO HNO3

Sodium nitrate Ammonium nitrate

NaNO3 NH4NO3

Nitromethane

CH3NO2


Conditions Vapor (0.5 MPa) Liquid (25°C), anhydrous Liquid (–50°C) Aqueous HNO3 Aqueous solution (saturated) 2.9 M (in 1 M HCl) 1.0 M (in 10 M HCl) Aqueous solution (saturated) Aqueous solution (saturated) Chloroform solution (saturated) Aqueous solution (0.3 M ) Aqueous solution (saturated) Chloroform solution (0.075 M ) Neat Neat 1M 2M 9M 10 M 15.7 M Aqueous solution (saturated) Aqueous solution (saturated) 5 M (in 2 M HNO3) 4 M (in 2 M HNO3) 1:1 (v/v) in CDCl3 0.03 M Cr(acac)3 Neat

Chemical Shift (ppm) –15.9 0.0 3.37 21.60 20.68 24.93 30.31 27.34 43.54 45.68 63.94 64.39 65.69 62.50 103.81 375.80 367.84 365.86 362.00 348.92 376.53 376.25 375.59 374.68 379.60 380.23


15

N CHEMICAL SHIFTS OF MAJOR CHEMICAL FAMILIES

The following table contains 15N chemical shifts of various organic nitrogen compounds. Chemical shifts are expressed relative to different standards (NH3, NH4Cl, CH3NO2, NH4NO3, HNO3, etc.) and are interconvertible. Chemical shifts are sensitive to hydrogen bonding and are solvent dependent, as seen in the case of pyridine (see table footnote b below). Consequently, the reference as well as the solvent should always accompany chemical shift data. No data are given on peptides and other biochemical compounds. All shifts are relative to ammonia unless otherwise specified. A section of miscellaneous data gives the chemical shift of special compounds relative to unusual standards.1–15

REFERENCES 1. Levy, G.C. and Lichter, R.L., Nitrogen-15 Nuclear Magnetic Resonance Spectroscopy, John Wiley & Sons, New York, 1979. 2. Yoder, C.H. and Schaeffer, C.D., Jr., Introduction to Multinuclear NMR, Benjamin/Cummings, Menlo Park, CA, 1987. 3. Duthaler, R.O. and Roberts, J.D., Effects of solvent, protonation, and N-alkylation on the 15N chemical shifts of pyridine and related compounds, J. Am. Chem. Soc., 100, 4969, 1978. 4. Duthaler, R.O. and Roberts, J.D., Steric and electronic effects on 15N chemical shifts of saturated aliphatic amines and their hydrochlorides, J. Am. Chem. Soc., 100, 3889, 1978. 5. Kozerski, L. and von Philipsborn, W., 15N chemical shifts as a conformational probe in enaminones: a variable temperature study at natural isotope abundance, Org. Magn. Reson., 17, 306, 1981. 6. Duthaler, R.O. and Roberts, J.D., Steric and electronic effects on 15N chemical shifts of piperidine and decahydroquinoline hydrochlorides, J. Am. Chem. Soc., 100, 3882, 1978. 7. Duthaler, R.O. and Roberts, J.D., Nitrogen-15 nuclear magnetic resonance spectroscopy: solvent effects on the 15N chemical shifts of saturated amines and their hydrochlorides, J. Magn. Reson., 34, 129, 1979. 8. Psota, L., Franzen-Sieveking, M., Turnier, J., and Lichter, R.L., Nitrogen nuclear magnetic resonance spectroscopy: nitrogen-15 and proton chemical shifts of methylanilines and methylanilinium ions, Org. Magn. Reson., 11, 401, 1978. 9. Subramanian, P.K., Chandra Sekara, N., and Ramalingam, K., Steric effects on nitrogen-15 chemical shifts of 4-aminooxanes (tetrahydropyrans), 4-amino-thianes, and the corresponding N,N-dimethyl derivatives: use of nitrogen-15 shifts as an aid in stereochemical analysis of these heterocyclic systems, J. Org. Chem., 47, 1933, 1982. 10. Schuster, I.I. and Roberts, J.D., Proximity effects on nitrogen-15 chemical shifts of 8-substituted 1nitronaphthalenes and 1-naphthylamines, J. Org. Chem., 45, 284, 1980. 11. Kupce, E., Liepins, E., Pudova, O., and Lukevics, E., Indirect nuclear spin-spin coupling constants of nitrogen-15 to silicon-29 in silylamines, J. Chem. Soc. Chem. Commun., 581, 1984. 12. Allen, M. and Roberts, J.D., Effects of protonation and hydrogen bonding on nitrogen-15 chemical shifts of compounds containing the >C=N-group, J. Org. Chem., 45, 130, 1980. 13. Brownlee, R.T.C. and Sadek, M., Natural abundance 15N chemical shifts in substituted benzamides and thiobenzamides, Magn. Reson. Chem., 24, 821, 1986. 14. Dega-Szafran, Z., Szafran, M., Stefaniak, L., Brevard, C., and Bourdonneau, M., Nitrogen-15 nuclear magnetic resonance studies of hydrogen bonding and proton transfer in some pyridine trifluoroacetates in dichloromethane, Magn. Reson. Chem., 24, 424, 1986. 15. Lambert, J.B., Shurvell, H.F., Verbit, L., Cooks, R.G., and Stout, G.H., Organic Structural Analysis, Macmillan, New York, 1976.



15

N Chemical Shifts of Major Chemical Families

Chemical Shift Range (ppm) C=N–OH (syn) >C=N–OH (anti)

Nitriles, salts Amides Anilines Pyridines Nitriles Pyridinium salts Pyrroles

~2 to ~1 to ~1 to ~0 to –1 to ~ –4 ~ –5

CH3C≡NH+ (2.8) CH3CONH2 (1.3) C6H5NH2 (1.5, 1.8) C5H5N (0.2) CH3C≡N (–1.7) C5H5NH+ (–3.98) C4H4NH (–5.39)


4 2 2 1 –2

NH3 CH3NH2 (–64.5) (CH3)2NH (–67.0) CH3NH3Cl (–75.4) (CH3)2NH2Cl (–76.1) C6H5NH3+ (–76) C6H5NH2 (–78.5) p-CH3O–C6H4–NH2 (–79.4) p-O2N–C6H4–NH2 (–92.6) C6H5SO2NH2 (–80.8) C6H5NHNH2 (–89.6) HCONH2 (–88) (syn); (–92) (anti) Pyrrole (–96.53) CH3C≡NH+ (–136)


15

N–13C Coupling Constants

Bond Type

JCH, H2

Family

One bond

Two bond

Three bond

15

Amines, aliphatic

~ –4

Ammonium salts, aliphatic Ammonium salts, aromatic Pyrroles Amines, aromatic Nitro compounds

~ –5 ~ –9 ~ –10 –11 to –15 –10 to –15

Nitriles Amides

~ –17 ~ –14

Amides Nitriles Pyridines and N-derivatives

7–9 ~3 ~1–3

Amines, aliphatic Nitro compounds, aromatic Amines, aromatic

~1–2 ~ –1 to –2 ~ –1 to –2

Pyrroles Amides Ammonium salts

~ –4 9 1–9

Pyridines Amines, aliphatic Amines, aromatic Nitro compounds Pyrroles

~3 1–3 ~ –1 to –3 ~ –2 ~ –4

Example CH3NH2 (–4.5) CH3(CH2)2NH2 (–3.9) CH3(CH2)2NH3+ (–4.4) C6H5NH3+ (–8.9) C4H4NH (–10.3) C6H5NH2 (–11.43) CH3NO2 (–10.5) C6H5NO2 (–14.5) CH3C≡N (–17.5) C6H5NHCOCH3 (–14.3) (CO); (–14.1) (C1) CH3CONH2 (9.5) CH3C≡N (3.0) C5H5N (2.53) C5H5NH+ (2.01) C5H5NO (1.43) CH3CH2CH2NH2 (1.2) C6H5NO2 (–1.67) C6H5NH2 (–2.68) C6H5NH3+ (–1.5) C4H4NH (–3.92) CH2=CHCONH2 (19) CH3(CH2)2NH3+ (1.3) C6H5NH3+ (2.1) C5H5N (2.53) CH3(CH2)2NH2 (1.4) C6H5NH2 (–2.68) C6H5NO2 (–1.67) C4H4NH (–3.92)

N–15N Coupling Constants Family

JNN, H2

Example

Azocompounds N-Nitrosamines Hydrazones Hydrazines

12–25 ~19 ~10 ~7

C6H5N=NC(CH3)2C6H5 (17) (anti); (21) (syn) (C6H5CH2)2N–N=0 (19) p-O2NC6H4CH=N–NHC6H5 (10.7) C6H5NHNH2 (6.7)

Bond Type

15

Bond Type

N–19F Coupling Constants Family Diflurodiazines trans cis Fluoropyridines 2-fluoro3-fluoroFluoroanilines 2-fluoro3-fluoro4-fluoroFluoroanilinium salts 2-fluoro3-fluoro4-fluoro-


JNF , H2 1

~190 ( JNF) ~102 (2JNF) ~203 (1JNF) ~52 (2JNF)

Example F–N=N–F F–N=N–F F–N=N–F F–N=N–F

(190) (102) (203) (52)

–52.5 +3.6 0 0 1.5

1,2-C6H4F (NH2) 1,3-C6H4F (NH2) 1,4-C6H4F (NH2)

1.4 0.2 0

1,2-C6H4F (NH3+) 1,3-C6H4F (NH3+) 1,4-C6H4F (NH3+)


19

F CHEMICAL SHIFT RANGES

The following table lists the 19F chemical shift ranges (in ppm) relative to neat CFCl3.1–4

REFERENCES 1. Yoder, C.H. and Schaeffer, C.D., Jr., Introduction to Multinuclear NMR: Theory and Application, Benjamin/Cummings, Menlo Park, CA, 1987. 2. http://nmrsg1.chem.indiana.edu/NMRguidemisc/19Fshifts.html. 3. Dungan, C.H. and Van Wazer, I.R., Compilation of Reported 19F Chemical Shifts 1951 to Mid 1967, Wiley Interscience, New York, 1970. 4. Emsley, J.W., Phillips, L., and Wray, V., Fluorine Coupling Constants, Pergamon, New York, 1977.

19

F Chemical Shift Ranges

Compound Type F–C(=O) –CF3 >CF2 –>CF Ar–F Ar = aromatic moiety


Chemical Shift Range (ppm) Relative to Neat CFCl3 –70 to –20 +40 to +80 +80 to +140 +140 to +250 +80 to +170


19

F CHEMICAL SHIFTS OF SOME FLUORINE-CONTAINING COMPOUNDS

The following table lists the 19F chemical shifts of some fluorine-containing compounds relative to neat CFCl3. All chemical shifts are those of neat samples, and the values pertain to the fluorine present in the molecule.1–3

REFERENCES 1. http://nmrsg1.chem.indiana.edu/NMRguidemisc/19Fshifts.html, 2003. 2. Dungan, C.H. and Van Wazer, I.R., Compilation of Reported 19F Chemical Shifts 1951 to Mid 1967, Wiley Interscience, New York, 1970. 3. Emsley, J.W., Phillips, L., and Wray, V., Fluorine Coupling Constants, Pergamon, New York, 1977.



19

F Chemical Shifts of Some Fluorine-Containing Compounds Compound CFCl3 CF4 CH3F CF3H CF3R CF2H2 CH3CH2F FCH=CH2 CF2=CH2 CF2=CF2 CF3COOH CF3COOC6H5 CF3COOCH2C6H5 CF3COOCH3 CF3COOCH2CH3 C 6F 6 C 6F 5H p-C6H4F2 C6H5–CH2F C6H5–CF3 C 4F 8 C5F10 CHF2OR (CF3)2CO F2 CF3Cl ClF3 ClF5 CF2Cl2 CFCl2–CFCl2 CFBr3 CF2Br2 IF7 AsF3 AsF5 BF3 (CH3)2O.BF3 (C2H5)2O.BF3 SF6 SO2F SbF5 SeF6 SiF4 TeF6 SF6 XeF2 XeF4 XeF6 NF3 POF3 PF3


Chemical Shift (ppm) 0.00 −62.3 −271.9 −78.6 −60 to −70 −143.6 −231 −114 − 81.3 −135 −78.5 −73.85 −75.02 −74.21 −78.7 −164.9 −113.5 −106.0 −207 −63.72 −135.15 −132.9 −82 −84.6 +422.92 –28.6 +116, −4 +247, +412 −8 −67.8 +7.38 +7 +170 −40.6 −66 −131.3 −158.3 −153 +57.42 −78.5 −108 +55 −163.3 −57 −57 +258 +438 +550 +147 −90.7 −67.5


FLUORINE COUPLING CONSTANTS The following table gives the most important fluorine coupling constants, namely, JFN, JFCF , and JCF , together with some typical examples.1–9 The coupling constant values vary with the solvent used.3 The book by Emsley et al.1 gives a complete, detailed list of various compounds.

REFERENCES 1. Emsley, J.W., Phillips, L., and Wray, V., Fluorine Coupling Constants, Pergamon Press, Oxford, 1977. 2. Lambert, J.R., Shurvell, H.F., Verbit, L., Cooks, R.G., and Stout, G.H., Organic Structural Analysis, Macmillan, New York, 1976. 3. Yoder, C.H. and Schaeffer, C.D., Jr., Introduction to Multinuclear NMR: Theory and Application, Benjamin/Cummings, Menlo Park, CA, 1987. 4. Schaeffer, T., Marat, K., Peeling, J., and Veregin, R.P., Signs and mechanisms of 13C, 19F spin-spin coupling constants in benzotrifluoride and its derivatives, Can. J. Chem., 61, 2779, 1983. 5. Adcock, W. and Kok, G.B., Polar substituent effects on 19F chemical shifts of aryl and vinyl fluorides: a fluorine-19 nuclear magnetic resonance study of some 1,1-difluoro-2-(4-substituted-bicyclo[2,2,2]oct1-yl)ethenes, J. Org. Chem., 50, 1079, 1985. 6. Newmark, R.A. and Hill, J.R., Carbon-13-fluorine-19 coupling constants in benzotrifluorides, Org. Magn. Reson., 9, 589, 1977. 7. Adcock, W. and Abeywickrema, A.N., Concerning the origin of substituent-induced fluorine-19 chemical shifts in aliphatic fluorides: carbon-13 and fluorine-19 nuclear magnetic resonance study of 1-fluoro-4-phenylbicyclo[2,2,2]octanes substituted in the arene ring, J. Org. Chem., 47, 2945, 1982. 8. Dungan, C.H. and Van Wazer, I.R., Compilation of Reported 19F Chemical Shifts 1951 to Mid 1967, Wiley Interscience, New York, 1970. 9. Emsley, J.W., Phillips, L., and Wray, V., Fluorine Coupling Constants, Pergamon Press, New York, 1977.



19

F–H Coupling Constants

Fluorinated Family

JFH

Alkanes

45–80

Alkyl chlorides

49–65

Alkyl bromides Alkenes

45–50 45–80

Aromatics

45–75

Ethers

40–75

Ketones

45–50

Aldehydes Esters

~50 45–70

Alkanes

2–25

Alkyl chlorides Alkyl bromides Alkenes

Alcohols

8–20 15–25 −5 to 60 JHCF (cisoid), 20 5–30

Ketones

5–25

Aldehydes Esters

10–25 10–25


Example Two Bond CH3F (45); CH2F2 (50); CHF3 (79); C2H5F (47); CH3CHF2 (57); CH2FCH2F (48); CH2FCHF2 (54); CF3CH2F (45); CF2HCF2CF3 (52) FCl2CH (53); CF2HCl (63); FCHCl–CHCl2 (49); FCH2–CH2Cl (46) FBrCHCH3 (50.5); FH2C–CH2Br (46); FBrCH–CHFBr (49) FHC=CHF (cis, 71.7; trans, 75.1); CH2=CHF (85); CF2=CHF (70.5); FCH2CH=CH2 (47.5) Cl–C6H4–CH2F (m-47, p-48); FH2C–C6H4–NO2 (m-47, p48); FH2C–C6H4–F (m-48, p-48); p-Br–C6H4–OCF2H (73) FH2COCH3 (74); CF2HCF2OCH3 (46); F2HC–O–CH(CH3)2 (75) FCH2COCH3 (47); F2HC–COCH3 (54); CH3CH2CHFCOCH3 (50); F2HC–COCH(CF3)2 (54) CH3CH2CHFCHO (51) CFH2CO2CH2CH3 (47); CH3CHFCO2CH2CH3 (48) Three Bond CF2HCH3 (21); (CH3)3CF (20.4); CH3CHFCH2CH2CH3 (23); CF3CH3 (13) CF2HCHCl2 (8); CF2ClCH3 (15) CF2BrCH2Br (22); CF2BrCH3 (16); FC(CH3)2CHBrCH3 (21) CHF=CHF (cis, 19.6; trans, 2.8); CH2=CHF (cis, 19.6; trans, 51.8); CHF=CF2 (cis, –4.2; trans, 12.5); CH2=CF2 (cis, 0.6; trans, 33.8) CF3CH2OH (8); FCH2CH2OH (29); CH3CHFCH2OH (23.6, 23.6); CF3CH(OH)CH3 (7.5); CF3CH(OH)CF3 (6); FC(CH3)2C(OH)(CH3)2 (23) CH3CH2CHFCOCH3 (24); FC(CH3)2COCH3 (21); (CF3)2CHCOCH3 (8); CF2HCOCH(CF3)2 (7) (CH3)2CFCHO (22) CH3CHFCO2CH2CH3 (23); (CH3CH2)2CFCO2CH3 (16.5)


19

F–19F Coupling

Carbon

JFCF

Saturated (sp3)

140–250

Cycloalkanes

150–240

Unsaturated (sp2)

≤100

Saturated (sp3)

0–16

Unsaturated (sp2)

>30

Examples Two Bond CF3CF2a,bCFHCH3 (Jab = 270); CF2a,bBrCHFSO2F (Jab = 188); CH3O–CF2a,bCFHSO2F (Jab = 147); CH3O–CF2a,bCFHCl (Jab = 142); CH3S–CF2a,bCFHCl (Jab = 222) F2C(CH2)2 (150) (three-membered) F2C(CH2)3 (200) (four-membered) F2C(CH2)4 (240) (five-membered) F2C(CH2)5 (228) (six-membered) CF2=CH2 (31, 36); CF2=CHF (87); CF2=CBrCl (30); CF2=CHCl (41); CF2=CFBr (75); CF2=NCF3 (82); CF2=CFCN (27); CF2=CFCOF (7); CF2=CFOCH2CF3 (102); CF2=CBrCH2N(CF3)2 (30); CF2=CFCOCF2CF3 (12); CF2=CHC6H5 (33); CF2=CH(CH2)5CH3 (50); CF2=CH–Ar[Ar=aryl] (50) Three Bond CF3CH2F (16); CF3CF3 (3.5); CF3CHF2 (3); CH2FCH2F (10–12); CF2aHCFbHCF2H (Jab = 13); CF2HCF2aCH2F (Jab = 14); CF3aCF2bCFcHCH3 (Jab < l; Jbc = 15); CF3aCFbHCF2cH (Jab = 12; Jbc = 12); CF3aCF2bC≡CF3 (Jab = 3.3); CF3aCF2bC≡CCF3 (Jab = 3.3); (CF3a)2CFbC≡CCl (Jab = 10); CF3CF2COCH2CH3 (1); FCH2CFHCO2C2H5 (–11.6); CF3aCF2bCF2cCOOH (Jab < l; Jbc < l); (CF3a)2CFbS(O)OC2H5 (Jab = 8) FCH=CHF (cis, –18.7; trans, –133.5); CF2=CHBr (34.5); CF2=CHCl (41); CF2=CH2 (37)

C–19F Coupling Fluorinated Family

JCF , H2

Alkanes

150–290

Alkenes

250–300

Alkynes Alkyl chlorides

250–260 275–350

Alkyl bromides

290–375

Acyl fluorides Carboxylic acids Alcohols Nitriles Esters Ketones Ethers

350–370 245–290 ~275 ~250 ~285 ~290 ~265


Examples One Bond CH3F (158); CH2F2 (237); CHF3 (274); CF4 (257); CF3CF3 (281); CF3CH3 (271); (CH3)3CF (167); (CaF3b)2CcF2d (Jab = 285; Jcd = 265) CF2=CD2 (287); CF2=CCl2 (–289); CF2=CBr2 (290); ClFC=CHCl (cis, –300; trans, –307); ClFC=CClF (cis, 290; trans, 290) CaF3bC≡CF (Jab = 259); CF3C≡CCF3 (256) CFCl3 (337); CF2Cl2 (325); CF3Cl (299); CF3(CCl2)2CF3 (286); CF3CH2Cl (274); CF3CCl=CCl2 (274);CF2=CCl2 (–289); CF3CCl3 (283) CFBr3 (372); CF2Br2 (358); CF3Br (324); CF3CH2Br (272); CF2=CBr2 (290) HCOF (369); CH3COF (353) CF3COOH (283); CF2HCO2H (247) CF3CH2OH (278) CF2HCN (244) CF3CO2CH2CH3 (284) CF3COCH3 (289) (CF3)2O (265)


RESIDUAL PEAKS OBSERVED IN THE 1H NMR SPECTRA OF COMMON DEUTERATED ORGANIC SOLVENTS The following table lists the residual peaks that are observed in the 1H NMR spectra of common deuterated organic solvents. These peaks are generally attributed to the nondeuterated parent compound that serves as an impurity and are marked with an asterisk. In addition, other less significant peaks often arise due to other impurities. Together with the formula and molecular weight, the table lists the expected chemical shifts, δ; multiplicities; and, when possible, the coupling constant, JHD, for every solvent. All spectra are at least 99.5% deuterium pure.1–5

REFERENCES 1. Yoder, C.H. and Schaeffer, C.D., Jr., Introduction to Multinuclear NMR, Benjamin Cummings, Menlo Park, CA, 1987. 2. Silverstein, R.M. and Webster, F.X., Spectrometric Identification of Organic Compounds, 6th ed., John Wiley & Sons, New York, 1998. 3. Gunther, H., NMR Spectroscopy: Basic Principles, Concepts and Applications in Chemistry, John Wiley & Sons, New York, 2003. 4. Lambert, J.B., Holland, L.N., and Mazzola, E.P., Nuclear Magnetic Resonance Spectroscopy: Introduction to Principles, Applications and Experimental Methods, Prentice Hall, Englewood Cliffs, NJ, 2003. 5. Nelson, J.H., Nuclear Magnetic Resonance Spectroscopy, 2nd ed., John Wiley & Sons, New York, 2003.



Residual Peaks Observed in the 1H NMR Spectra of Common Deuterated Organic Solvents Solvent

Formula

Molecular Weight

Acetic acid-d4

CD3COOD

64.078

Acetone-d6

(CD3)2C=O

64.117

Acetonitrile-d3

CD3CN

44.017

Benzene-d6 Chloroform-d3

C 6D 6 CDCl3

84.153 120.384

Cyclohexane-d12 Deuterium oxide

(CD2)6 D20

96.236 20.028

1,2-Dichloroethane-d4 Dichloromethane-d2 Diethylene glycol dimethylether-d14 Diethylether-d10

CD2ClCD2Cl See Methylene chloride-d2

Diglyme-d14

CD3O(CD2)2O(CD2)2OCD3

N,N-Dimethylformamide-d7

DCON(CD3)2

Dimethylsulfoxide-d6

(CD3)2SO

1,2-Diethoxyethane-d10

See Glyme-d10

p-Dioxane-d8 Ethanol-d6 (anhydrous)

C4H8O2 CD3CD2OD

Glyme-d10

CD2OCD2CD2OCD3

100.184

Hexamethylphosphoric triamide-d18 (HMPT-d18) Methanol-d4

[(CD3)2N]3P=O

197.314

CD3OH

36.067

Methylene chloride-d2

CD2Cl2

86.945

Nitrobenzene-d5

C6D5NO2

Nitromethane-d3 2-Propanol-d8

CD3NO2 (CD3)2CDOD

64.059 68.146

Pyridine-d5

C6D5N

84.133


See Diglyme-d14 (CD3CD2)2O

102.985

84.185 148.263

80.138

96.156 52.106

128.143

δ (mult)a *11.53 (1) *2.03 (5) *2.04 (5) 2.78 (1) 2.82 (1) *1.93 (5) 2.1–2.15 2.2–2.4 *7.12 (b) 1.55b 1.60b 7.2 *7.24 (1) *1.38 (b) *4.63 (b)c *4.67 (b)d *3.72 (b)

*3.34 (m) *1.07 (m) *3.49 (b) *3.40 (b) *3.22 (5) *8.01 (b) *2.91 (5) *2.74 (5) 3.3–3.4 *2.49 (5)

*3.53 *5.19 *3.55 *1.11 *3.40 *3.22 *2.53

(m) (1) (b) (m) (m) (5) (m)

*4.78 (1) *3.30 (5) *5.32 (3) 1.4–1.5 (b) *8.11 (b) *7.67 (b) *7.50 (b) *4.33 (5) *5.12 (1) *3.89 (b) *1.10 (b) *8.71 (b) *7.55 (b) *7.19 (b) 4.8b 4.9b

JHD 2 2.2

2.5

1.5

2 2 1.7

1.6

1.7 1

2


Residual Peaks Observed in the 1H NMR Spectra of Common Deuterated Organic Solvents (continued) Solvent

Formula

Molecular Weight

Tetrahydrofuran-d8

C4D8O

Toluene-d8

C6D5CD3

100.191

Trifluorocetic acid-d

CF3COOD

115.030

a

b c

d

80.157

δ (mult)a

JHD

*3.58 (b) 2.4b 2.3b *1.73 (b) *7.09 (m) *7.00 (b) *6.98 (m) *2.09 (5) *11.50 (1)

2.3

Chemical shift, δ, in ppm; mult = multiplicity (indicated by a number); b = broad, m = multiplet. Two peaks that may often appear as one broad peak. When DSS, 3-(trimethylsilyl)-1-propane sulfonic acid, sodium salt, is used as a reference standard. When TSP, sodium-3-trimethylpropionate, is used as a reference standard.



CHAPTER

10

Mass Spectrometry

CONTENTS Natural Abundance of Important Isotopes Rules for Determination of Molecular Formula Neutral Moieties Ejected from Substituted Benzene Ring Compounds Order of Fragmentation Initiated by the Presence of a Substituent on a Benzene Ring Chlorine–Bromine Combination Isotope Intensities Reference Compounds under Electron Impact Conditions in Mass Spectrometry Major Reference Masses in the Spectrum of Heptacosafluorotributylamine (Perfluorotributylamine) Common Fragmentation Patterns of Families of Organic Compounds Common Fragments Lost Important Peaks in the Mass Spectra of Common Solvents Reagent Gases for Chemical Ionization Mass Spectrometry Proton Affinities of Some Simple Molecules Proton Affinities of Some Anions Detection of Leaks in Mass Spectrometer Systems Mass Resolution Required to Resolve Common Spectral Interferences Encountered in Inductively Coupled Plasma Mass Spectrometry



NATURAL ABUNDANCE OF IMPORTANT ISOTOPES The following table lists the atomic masses and relative percent concentrations of naturally occurring isotopes of importance in mass spectrometry.1–5

REFERENCES 1. deHoffmann, E. and Stroobant, V., Mass Spectrometry: Principles and Applications, 2nd ed., John Wiley & Sons, Chichester, U.K., 2001. 2. Johnstone, R.A.W. and Rose, M.E., Mass Spectrometry for Chemists and Biochemists, Cambridge University Press, Cambridge, U.K., 1996. 3. Lide, D.R., Ed., CRC Handbook of Chemistry and Physics, 83rd ed., CRC Press, Boca Raton, FL, 2002. 4. McLafferty, F.W. and Turecek, F., Interpretation of Mass Spectra, 4th ed., University Science Books, Mill Valley, CA, 1993. 5. Watson, J.T., Introduction to Mass Spectrometry, 3rd ed., Lippincott-Raven, Philadelphia, 1997. Natural Abundance of Important Isotopes Element Hydrogen Boron Carbon Nitrogen Oxygen Fluorine Silicon Phosphorus Sulfur Chlorine Bromine Iodine

Total No. of Isotopes 3 6 7 7 8 6 8 7 10 11 17 23


More Prominent Isotopes (Mass, Percent Abundance) 1

2

10

11

H (1.00783, 99.985) B (10.01294, 19.8) 12C (12.00000, 98.9) 14N (14.00307, 99.6) 16O (15.99491, 99.8) 19F (18.99840, ≈100.0) 28Si (27.97693, 92.2) 31P (30.97376, ≈100.0) 32S (31.972017, 95.0) 35Cl (34.96885, 75.5) 79Br (78.9183, 50.5) 127I (126.90466, ≈100.0)

H (2.01410, 0.015) B (11.00931, 80.2) 13C (13.00335, 1.1) 15N (15.00011, 0.4) 18

O (17.9992, 0.2) Si (29.97376, 3.1)

29

Si (28.97649, 4.7)

30

33

S (32.97146, 0.7)

34

S (33.96786, 4.2) Cl (36.96590, 24.5) 81Br (80.91642, 49.5) 37


RULES FOR DETERMINATION OF MOLECULAR FORMULA The following rules are used in the mass spectrometric determination of the molecular formula of an organic compound.1–5 These rules should be applied to the molecular ion peak and its isotopic cluster. The molecular ion, in turn, is usually the highest mass in the spectrum. It must be an oddelectron ion and must be capable of yielding all other important ions of the spectrum via a logical neutral species loss. The elements that are assumed to possibly be present on the original molecule are carbon, hydrogen, nitrogen, the halogens, sulfur, and oxygen. The molecular formula that can be derived is not the only possible one, and consequently, information from nuclear magnetic resonance spectrometry and infrared spectrophotometry is necessary for the final molecular formula determination. Modern mass spectral databases allow the automated searching of very extensive mass spectral libraries.6 This has made the identification of compounds by mass spectrometry a far more straightforward task. One must understand, however, that such databases are no substitute for the careful analysis of each mass spectrum and that the results of database matchup are merely suggestions.

REFERENCES 1. 2. 3. 4. 5.

Lee, T.A., A Beginner’s Guide to Mass Spectral Interpretation, Wiley, New York, 1998. McLafferty, F.W., Interpretation of Mass Spectra, University Science Books, Mill Valley, CA, 1993. Shrader, S.R., Introductory Mass Spectrometry, Allyn and Bacon, Boston, 1971. Smith, R.M., Understanding Mass Spectra: A Basic Approach, Wiley, New York, 1999. Watson, J.T. and Watson, T.J., Introduction to Mass Spectrometry, Lippincott, Williams & Wilkins, Philadelphia, 1998. 6. NIST Standard Reference Database 1A, NIST/EPA/NIH Mass Spectral Library with Search Program (Data Version: NIST ’02, Software Version 2.0).

Rule 1: An odd molecular ion value suggests the presence of an odd number of nitrogen atoms; an even molecular ion value is due to the presence of zero, or an even number of nitrogen atoms. Thus, m/e = 141 suggests 1, 3, 5, 7, etc., nitrogen atoms, while m/e = 142 suggests 0, 2, 4, 6, etc., nitrogen atoms. Rule 2: The maximum number of carbons (Ncmax) can be calculated from the formula ( N Cmax ) =

Relative intensity of M + 1 peak 100 × Relative intensity of M + peak 1.1

where M + 1 is the peak one unit above the value of the molecular ion (M+). This rule gives the maximum number of carbons, but not necessarily the actual number. If, for example, the relative intensities of M+ and M + 1 are 100 and 9% respectively, then the maximum number of carbons is (NCmax) = (9/100) × (100 /1.1) = 8 In this case there is a possibility for seven, six, etc., carbons, but not for nine or more.



Rule 3: The maximum numbers of sulfur atoms (NSmax) can be calculated from the formula ( N Smax ) =

Relative intensity of M+ 2 peak 100 × Relative intensity of M+ peak 4.4

where M + 2 is the peak two units above that of the molecular ion M+. Rule 4: The actual number of chlorine and bromine atoms can be derived from the table that follows later in this chapter. Rule 5: The difference should be only oxygen and hydrogen atoms. These rules assume the absence of phosphorus, silicon, or any other elements.



NEUTRAL MOIETIES EJECTED FROM SUBSTITUTED BENZENE RING COMPOUNDS The following table lists the most common substituents encountered in benzene rings and the neutral particles lost and observed on the mass spectrum.1 Complex rearrangements are often encountered and enhanced by the presence of one or more heteroatomic substituent(s) in the aromatic compound. All neutral particles that are not the product of rearrangement appear in parentheses and are produced alongside the species that are formed via rearrangement. Prediction of the more abundant moiety is not easy, as it is seriously affected by factors that dictate the nature of the compound. These include the nature and the position of any other substituents, as well as the stability of any intermediate(s) formed. Correlations of the data with the corresponding Hammett σ constants have been neither consistent nor conclusive.

REFERENCES 1. Rose, M.E. and Johnstone, R.A.W., Mass Spectroscopy for Chemists and Biochemists, Cambridge University Press, Cambridge, U.K., 1982. Neutral Moieties Ejected from Substituted Benzene Ring Compounds Substituent NO2 NH2 NHCOCH3 CN F OCH3 OH SO2NH2 SH SCH3


Neutral Moieties Ejected after Rearrangement NO, CO, (NO2) HCN C2H2O, HCN HCN C 2H 2 CH2O, CHO, CH3 CO, CHO SO2, HCN CS, CHS (SH) CS, CH2S, SH, (CH3)


ORDER OF FRAGMENTATION INITIATED BY THE PRESENCE OF A SUBSTITUENT ON A BENZENE RING The following table lists the relative order of ease of fragmentation that is initiated by the presence of a substituent in the benzene ring in mass spectrometry.1 The ease of fragmentation decreases from top to bottom. The substituents marked with an asterisk are very similar in their ease of fragmentation. Particularly in the case of disubstituted benzene rings, the order of fragmentation at the substituent linkage may be easily predicted using this table. As a rule of thumb, the more complex the size of the substituent, the easier is its decomposition. For instance, in all chloroacetophenone isomers (1,2-, 1,3-, or 1,4-), the elimination of the methyl radical occurs before the loss of chlorine. On the other hand, under normal mass conditions, all bromofluorobenzenes (1,2-, 1,3-, and 1,4-) easily lose the bromine but not the fluorine. Deuterium labeling studies have indicated that any rearrangement of the benzene compounds occurs in the molecular ion and before fragmentation.

REFERENCES 1. Rose, M.E. and Johnstone, R.A.W., Mass Spectroscopy for Chemists and Biochemists, Cambridge University Press, Cambridge, U.K., 1982. Order of Fragmentation Initiated by the Presence of a Substituent on a Benzene Ring Substituent COCH3 CO2CH3 NO2 *I *OCH3 *Br OH CH3 Cl NH2 CN F


Neutral Moiety Eliminated CH3 OCH3 NO2 I CH2O, CHO Br CO, CHO H Cl HCN HCN C 2H 2


CHLORINE–BROMINE COMBINATION ISOTOPE INTENSITIES Due to the distinctive mass spectral patterns caused by the presence of chlorine and bromine in a molecule, interpretation of a mass spectrum can be much easier if the results of the relative isotopic concentrations are known. The following table provides peak intensities (relative to the molecular ion (M+) at an intensity normalized to 100%) for various combinations of chlorine and bromine atoms, assuming the absence of all other elements except carbon and hydrogen.1–4 The mass abundance calculations were based on the most recent atomic mass data.1

REFERENCES 1. Lide, D.R., CRC Handbook of Chemistry and Physics, 83rd ed., CRC Press, Boca Raton, FL, 2002. 2. McLafferty, F.W., Interpretation of Mass Spectra, 4th ed., University Science Books, Mill Valley, CA, 1993. 3. Silverstein, R.H., Bassler, G.C., and Morrill, T.C., Spectroscopic Identification of Organic Compounds, 6th ed., John Wiley & Sons, New York, 1998. 4. Williams, D.H. and Fleming, I., Spectroscopic Methods in Organic Chemistry, 4th ed., McGraw-Hill, London, 1989.



Relative Intensities of Isotope Peaks for Combinations of Bromine and Chlorine (M+ = 100%) Br0

Br1

Br2

Br3

Br4

98.0

196.0 96.1

294.0 288.2 94.1

390.8 574.7 375.3 92.0

32.5

130.6 31.9

228.0 159.0 31.2

326.1 383.1 187.4 30.7

424.6 704.2 564.1 214.8 30.3

2 4 6 8 10 12

65.0 10.6

163.0 74.4 10.4

261.1 234.2 83.3 10.2

359.3 490.2 312.8 91.7 9.8

456.3 840.3 791.6 397.5 99.2 10.1

+ + + + + + +

2 4 6 8 10 12 14

97.5 31.7 3.4

195.3 127.0 34.4 3.3

294.0 99.7 159.4 37.1 3.2

393.3 609.8 473.8 193.9 39.6 3.0

489 989 1064 654 229 42 3.2

P P P P P P P

+ + + + + + +

2 4 6 8 10 12 14

130.0 63.3 13.7 1.2

228.3 190.9 75.8 14.4 1.1

326.6 414.9 263.1 88.8 15.4 1.3

4.2 735.3 670.0 347.1 102.2 16.2 0.7

522 1149 1388 1002 443 117 17

Cl5

P P P P P P P

+ + + + + + +

2 4 6 8 10 12 14

162.6 105.7 34.3 5.5 0.3

260.7 265.3 137.9 39.3 5.8 0.3

358.9 520.8 397.9 174.5 44.3 5.7 0.5

Cl6

P P P P P P

+ + + + + +

2 4 6 8 10 12

195.3 158.6 68.8 16.6 2.1 0.1

Cl7

P P P P P P P

+ + + + + + +

2 4 6 8 10 12 14

227.8 222.1 120.3 39.0 7.5 0.8 0.05

Cl0

P P P P

+ + + +

2 4 6 8

Cl1

P P P P P

+ + + + +

2 4 6 8 10

Cl2

P P P P P P

+ + + + + +

Cl3

P P P P P P P

Cl4



REFERENCE COMPOUNDS UNDER ELECTRON IMPACT CONDITIONS IN MASS SPECTROMETRY The following table lists the most popular reference compounds for use under electron impact conditions in mass spectrometry. For accurate mass measurements, the reference compound is introduced and ionized concurrently with the sample and the reference peaks are resolved from sample peaks. Reference compounds should contain as few heteroatoms and isotopes as possible. This is to facilitate the assignment of reference masses and minimize the occurrence of unresolved multiplets within the reference spectrum.1 An approximate upper mass limit should assist in the selection of the appropriate reference.1,2

REFERENCES 1. Chapman, J.R., Computers in Mass Spectrometry, Academic Press, London, 1978. 2. Chapman, J.R., Practical Organic Mass Spectrometry, 2nd ed., John Wiley & Sons, Chichester, U.K., 1995. Reference Compounds under Electron Impact Conditions in Mass Spectrometry Reference Compound Perfluoro-2-butyltetrahydrofuran Decafluorotriphenyl phosphine (ultramark 443; DFTPP) Heptacosafluorotributylamine (perfluoro tributylamine; heptacosa; PFTBA) Perfluoro kerosene, low-boiling (perfluoro kerosene-L) Perfluoro kerosene, high-boiling (perfluoro kerosene-H) Tris (trifluoromethyl)-s-triazine Tris (pentafluoroethyl)-s-triazine Tris (heptafluoropropyl)-s-triazine Tris (perfluoroheptyl)-s-triazine Tris (perfluorononyl)-s-triazine Ultramark 1621 (fluoroalkoxy cyclotriphosphazine mixture) Fomblin diffusion pump fluid (ultramark F-series; perfluoropolyether)


Formula

Upper Mass Limit

C8F16O (C6F5)3P

416 443

(C4F9)3N

671

CF3(CF2)nCF3

600

CF3(CF2)nCF3

800–900

C3N3(CF3)3 C3N3(CF2CF3)3 C3N3(CF2CF2CF3)3 C3N3[(CF2)6CF3]3 C3N3[(CF2)8CF3]3 P3N3[OCH2(CF2)nH]6

285 435 585 1185 1485 ~2000

CF3O[CF(CF3)CF2O]m(CF2O)nCF3

≥3000


MAJOR REFERENCE MASSES IN THE SPECTRUM OF HEPTACOSAFLUOROTRIBUTYLAMINE (PERFLUOROTRIBUTYLAMINE) The following list tabulates the major reference masses (with their relative intensities and formulas) of the mass spectrum of heptacosafluorotributylamine.1 This is one of the most widely used reference compounds in mass spectrometry.

REFERENCES 1. Chapman, J.R., Practical Organic Mass Spectrometry, 2nd ed., John Wiley & Sons, Chichester, U.K., 1995. Major Reference Masses in the Spectrum of Heptacosafluorotributylamine (Perfluorotributylamine) Mass

Relative Intensity

Formula

Mass

Relative Intensity

Formula

613.9647 575.9679 537.9711 501.9711 463.9743 425.9775 413.9775 375.9807 325.9839 313.9839 263.9871 230.9856 225.9903 218.9856 213.9903

2.6 1.7 0.4 8.6 3.8 2.5 5.1 0.9 0.4 0.4 10 0.9 0.6 62 0.6

C12F24N C12F22N C12F20N C9F20N C9F18N C9F16N C8F16N C8F14N C7F12N C6F12N C5F10N C 5F 9 C 5F 8N C 4F 9 C 4F 8N

180.9888 175.9935 168.9888 163.9935 161.9904 149.9904 130.9920 118.9920 113.9967 111.9936 99.9936 92.9952 68.9952 49.9968 30.9984

1.9 1.0 3.6 0.7 0.3 2.1 31 8.3 3.7 0.7 12 1.1 100 1.0 2.3

C 4F 7 C 4F 6N C 3F 7 C 3F 6N C 4F 6 C 3F 6 C 3F 5 C 2F 5 C 2F 4N C 3F 4 C 2F 4 C 3F 3 CF3 CF2 CF



COMMON FRAGMENTATION PATTERNS OF FAMILIES OF ORGANIC COMPOUNDS The following table provides a guide to the identification and interpretation of commonly observed mass spectral fragmentation patterns for common organic functional groups.1–9 It is, of course, highly desirable to augment mass spectroscopic data with as much other structural information as possible. Especially useful in this regard will be the confirmatory information of infrared and ultraviolet spectrophotometry, as well as nuclear magnetic resonance spectrometry.

REFERENCES 1. Bowie, J.H., Williams, D.H., Lawesson, S.O., Madsen, J.O., Nolde, C., and Schroll, G., Studies in mass spectrometry. XV. Mass spectra of sulphoxides and sulphones: the formation of C–C and C–O bonds upon electron impact, Tetrahedron, 22, 3515, 1966. 2. Johnstone, R.A.W. and Rose, M.E., Mass Spectrometry for Chemical and Biochemists, Cambridge University Press, Cambridge, U.K., 1996. 3. Lee, T.A., A Beginner’s Guide to Mass Spectral Interpretation, Wiley, New York, 1998. 4. McLafferty, F.W., Interpretation of Mass Spectra, 4th ed., University Science Books, Mill Valley, CA, 1993. 5. Pasto, D.J. and Johnson, C.R., Organic Structure Determination, Prentice Hall, Englewood Cliffs, NJ, 1969. 6. Silverstein, R.M., Bassler, G.C., and Morrill, T.C., Spectroscopic Identification of Organic Compounds, 6th ed., John Wiley & Sons, New York, 1998. 7. Smakman, R. and deBoer, T.J., The mass spectra of some aliphatic and alicyclic sulphoxides and sulphones, Org. Mass Spectrosc., 3, 1561, 1970. 8. Smith, R.M., Understanding Mass Spectra: A Basic Approach, Wiley, New York, 1999. 9. Watson, T.J. and Watson, J.T., Introduction to Mass Spectrometry, Lippincott, Williams & Wilkins, Philadelphia, 1997.



Common Fragmentation Patterns of Families of Organic Compounds Family

Molecular Ion Peak

Acetals Alcohols

Weak for 1 and 2°; not detectable for 3°; strong for benzyl alcohols

Aldehydes

Low intensity

Alkanes Chain Branched

Low intensity Low intensity

Alicyclic Alkenes (olefins) Alkyl halides

Fluorides Chlorides Bromides Iodides Alkynes Amides

Rather intense Rather high intensity (loss of π-electron) especially in case of cyclic olefins Abundance of molecular ion F < Cl < Br < I; intensity decreases with increase in size and branching Very low intensity Low intensity; characteristic isotope cluster Low intensity; characteristic isotope cluster Higher than other halides Rather high intensity (loss of π-electron) Rather high intensity

Amines

Hardly detectable in case of acyclic aliphatic amines; high intensity for aromatic and cyclic amines

Aromatic hydrocarbons (arenes)

Rather intense

Carboxylic acids

Weak for straight-chain monocarboxylic acids; large if aromatic acids Rather low intensity

Disulfides Phenols Sulfides (thioethers) Sulfonamides

Highly intense peak (base peaka generally) Rather low intensity peak but higher than that of corresponding ether Rather intense


Common Fragments and Characteristic Peaks Cleavage of all C–O, C–H, and C–C bonds around the original aldehydic carbon Loss of 18 (H2O — usually by cyclic mechanism); loss of H2O and olefin simultaneously with four (or more) carbonchain alcohols; prominent peak at m/e = 31 (CH2ÖH)+ for 1° alcohols; prominent peak at m/e = (RCHÖH)+ for 2° and m/e = (R2CÖH)+ for 3° alcohols Loss of aldehydic hydrogen (strong M-1 peak, especially with aromatic aldehydes); strong peak at m/e = 29 (HC≡O+); loss of chain attached to alpha carbon (beta cleavage); McLafferty rearrangement via beta cleavage if gamma hydrogen is present Loss of 14 units (CH2) Cleavage at the point of branch; low intensity ions from random rearrangements Loss of 28 units (CH2=CH2) and side chains Loss of units of general formula CnH2n–1; formation of fragments of the composition CnH2n (via McLafferty rearrangement); retro Diels–Alder fragmentation Loss of fragments equal to the mass of the halogen until all halogens are cleaved off

Loss of 20 (HF); loss of 26 (C2H2) in case of fluorobenzenes Loss of 35 (Cl) or 36 (HCl); loss of chain attached to the gamma carbon to the carbon carrying the Cl Loss of 79 (Br); loss of chain attached to the gamma carbon to the carbon carrying the Br Loss of 127 (I) Fragmentation similar to that of alkenes Strong peak at m/e = 44 indicative of a 1° amide + + (O=C=NH2); base peak at m/e = 59 (CH2=C(OH)NH2); possibility of McLafferty rearrangement; loss of 42 (C2H2O) for amides of the form RNHCOCH3 when R is aromatic ring Beta cleavage yielding >C=NC=O (alpha cleavage); peak at m/e = 43 for all methyl ketones (CH3CO+); McLafferty rearrangement via beta cleavage if gamma hydrogen is present; loss of m/e = 28 (C=O) for cyclic ketones after initial alpha cleavage and McLafferty rearrangement Similar to those of alcohols (–OH substituted by –SH); loss of m/e = 45 (CHS) and m/e = 44 (CS) for aromatic thiols M + 1 ion may appear (especially at higher pressures); M – 1 peak is weak but detectable (R–CH=C=N+); base peak at m/e = 41 (CH2=C=N H); McLafferty rearrangement + possible; loss of HCN is case of cyanobenzenes Base peak at m/e = 30 (NO+); large peak at m/e = 60 + (CH2=ONO) in all unbranched nitrites at the alpha carbon; absence of m/e = 46 permits differentiation from nitro compounds Loss of 30 (NO); subsequent loss of CO (in case of aromatic nitro compounds); loss of NO2 from molecular ion peak Similar to sulfoxides; loss of mass equal to RSO2; aromatic heterocycles show peaks at M-32 (sulfur), M-48 (SO), M64 (SO2) Loss of 17 (OH); loss of alkene (m/e equal to RSOH+) peak at m/e = 63 (CH2=SOH+); aromatic sulfoxides show peak at m/e = 125 (+S–CH=CHCH=CHC=O), 97 (C5H5S+), 93 (C6H5OH); aromatic heterocycles show peaks at M-16 (oxygen), M-29 (COH), M-48 (SO)

The base peak is the most intense peak in the mass spectrum and is often the molecular ion peak, M +.



COMMON FRAGMENTS LOST The following table gives a list of neutral species that are most commonly lost when measuring the mass spectra of organic compounds. The list is suggestive rather than comprehensive and should be used in conjunction with other sources.1–4 The listed fragments include only combinations of carbon, hydrogen, oxygen, nitrogen sulfur, and the halogens.

REFERENCES 1. Hamming, M. and Foster, N., Interpretation of Mass Spectra of Organic Compounds, Academic Press, New York, 1972. 2. McLafferty, F.W., Interpretation of Mass Spectra, 4th ed., University Science Books, Mill Valley, CA, 1993. 3. Silverstein, R.M., Bassler, G.C., and Morrill, T.C., Spectroscopic Identification of Organic Compounds, 6th ed., John Wiley & Sons, New York, 1996. 4. Bruno, T.J., CRC Handbook for the Analysis and Identification of Alternative Refrigerants, CRC Press, Boca Raton, FL, 1995. Common Fragments Lost Mass Lost

Fragment Lost ·

Mass Lost

Fragment Lost ·

1 15 17 18 19

H CH3· OH· H2O F·

51 52 54 55 56

20 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

HF HC≡CH; ·C≡N CH2–CH·; HC≡N CH2=CH2; C=O; (HCN and H·) CH3CH2·; H–·C=O ·CH NH ; HCHO; NO 2 2 CH3O·; ·CH2OH; CH3NH2 CH3OH; S HS· H2S Cl· HCl2H2O H2Cl C3H2·; C2N; F2 C3H3; HC2N CH3C≡CH CH2=CHCH2· CH2=CHCH3; CH2=C=O; (CH2)3; NCO; NCNH2 C3H7·; CH3C=O·; CH2=CH–O·; HCNO CH2=CHOH; CO2; N2O; CONH2; NHCH2CH3 CH3CHOH; CH3CH2O·; CO2H; CH3CH2NH2 CH3CH2OH; ·NO2 CH3S· CH3SH; SO; O3 ·CH Cl 2

57 58 59 60 61 62 63 64 68 69 71 73 74 75 76 77 78 79

CHF2 C4H4·, C2N2 CH2=CHCH=CH2 CH2=CH–CH·CH3 CH2=CH–CH2CH3; CH3CH=CHCH3; CO (2 mol) C4H9· ·NCS; (CH3)2C=O; (NO and CO) CH3OC≡O·; CH3CONH2; C2H3S· C3H7OH CH3CH2S·; (CH2)2S·H [H2S and CH2=CH2] ·CH CH Cl 2 2 S2·, SO2·, C5H4· CH2=CHC(CH3)=CH2 CF3·; C5H9· C5H11· CH3CH2OC·=O C4H9OH C 6H 3 C6H4; CS2 C6H5; HCS2 C6H6·, H2CS2·, C5H4N Br·; C5H5N

80 85

HBr ·CClF 2

43 44 45 46 47 48 49


100

CF2=CF2

119 122 127 128

CF3CF2· C6H5CO2H I· HI


IMPORTANT PEAKS IN THE MASS SPECTRA OF COMMON SOLVENTS The following table gives the most important peaks that appear in the mass spectra of the most common solvents, which may be found as impurities in organic samples. The solvents are classified in ascending order, based on their M+ peaks. The highest intensity peaks are indicated with the parenthetical 100%.1–4

REFERENCES 1. Clere, J.T., Pretsch, E., and Seibl, J., Studies in Analytical Chemistry. I. Structural Analysis of Organic Compounds by Combined Application of Spectroscopic Methods, Elsevier, Amsterdam, 1981. 2. McLafferty, F.W., Interpretation of Mass Spectra, 4th ed., University Science Books, Mill Valley, CA, 1993. 3. Pasto, D.J. and Johnson, C.R., Organic Structure Determination, Prentice Hall, Englewood Cliffs, NJ, 1969. 4. Smith, R.M., Understanding Mass Spectra: A Basic Approach, Wiley, New York, 1999.

Important Peaks in the Mass Spectra of Common Solvents Solvents

Formula

M+

Important Peaks (m/e)

(100%)

17 31 (100%), 29, 15 40, 39, 38, 28, 15 45, 31 (100%), 27, 15 45, 29, 15 43 (100%), 42, 39, 27, 15 45, 43, 18, 15 43, 33, 31 (100%), 29, 18, 15 42, 39, 38, 31, 29, 18 71, 43, 42 (100%), 41, 40, 39, 27, 18, 15 57, 43 (100%), 42, 41, 39, 29, 28, 27, 15 58, 44, 42, 30, 29, 28, 18, 15

Water Methanol Acetonitrile Ethanol Dimethylether Acetone Acetic acid Ethylene glycol Furan Tetrahydrofuran n-Pentane Dimethylformamide (DMF) Diethylether Methylacetate Carbon disulfide Benzene Pyridine Dichloromethane Cyclohexane n-Hexane

H 2O CH3OH CH3CN CH3CH2OH CH3OCH3 CH3COCH3 CH3CO2H HOCH2CH2OH C 4H 4O C 4H 8O C5H12 HCON(CH3)2

18 32 41 46 46 58 60 62 68 72 72 73

(C2H5)2O CH3CO2CH3 CS2 C 6H 6 C 5H 5N CH2Cl2 C6H12 C6H14

74 74 76 (100%) 78 (100%) 79 (100%) 84 84 86

1,4-Dioxane Tetramethylsilane (TMS) 1,2-Dimethoxy ethane Toluene Chloroform Chlorodorm-d1 Carbon tetrachloride

C 4H 8O 2 (CH3)4Si (CH3OCH2)2 C6H5CH3 CHCl3 CDCl3 CCl4

88 (100%) 88 90 92 118 119 152 (not seen)

Tetrachloroethene

CCl2=CCl2

164 (not seen)


(100%) (100%)

(100%)

(100%)

59, 45, 41, 31 (100%), 29, 27, 15 59, 43 (100%), 42, 32, 29, 28, 15 64, 44, 32 77, 52, 51, 50, 39, 28 80, 78, 53, 52, 51, 50, 39, 26 86, 51, 49 (100%), 48, 47, 35, 28 69, 56, 55, 43, 42, 41, 39, 27 85, 71, 69, 57 (100%), 43, 42, 41, 39, 29, 28, 27 87, 58, 57, 45, 43, 31, 30, 29, 28 74, 73, 55, 45, 43, 29 60, 58, 45 (100%), 31, 29 91 (100%), 65, 51, 39, 28 120, 83, 81 (100%), 47, 35, 28 121, 84, 82 (100%), 48, 47, 35, 28 121, 119, 117 (100%), 84, 82, 58.5, 47, 35, 28 168, 166 (100%), 165, 164, 131, 129, 128, 94, 82, 69, 59, 47, 31, 24


REAGENT GASES FOR CHEMICAL IONIZATION MASS SPECTROMETRY The following tables provide guidance in the selection and optimization of reagents in high-pressure chemical ionization mass spectrometry, as applied with gas chromatography or as a stand-alone technique.1–3 The first table provides data on positive ion reagent gases, which are called Bronsted acid reagents. Here, we provide the proton affinity (PA) of the conjugate base, the hydride ion affinity (the enthalpy of the reaction of the positive ion with H–). The second table provides data on negative ion reagent gases, which are called Bronsted base reagents. Here, we provide the proton affinity of the negative ion and the electron affinity of the base.

REFERENCES 1. Harrison, A.G., Chemical Ionization Mass Spectrometry, CRC Press, Boca Raton, FL, 1992. 2. Message, G.M., Practical Aspects of Gas Chromatography/Mass Spectrometry, John Wiley & Sons (Wiley Interscience), New York, 1984. 3. Karasek, F.W. and Clement, R.E., Basic Gas Chromatography–Mass Spectrometry, Elsevier, Amsterdam, 1988. Positive Ion Reagent Gases for Chemical Ionization Mass Spectrometry Reagent Gas

Reactant Ion(s) +

PA, kj/mol

PA, kcal/mol

HIA, kj/mol

HIA, kcal/mol

H2 N2 + H 2 CO2 + H2 N 2O + H 2 CO + H2 CH4

H3 N 2H + CO2H+ N2OH+2 HCO+ CH5+ C2H5+

423.7 494.9 547.6 581.1 596.2 551.0 680.8

101.2 118.2 130.8 138.8 142.4 131.6 162.6

1260 1180 1130 1090 1080 1130 1130

300 282 270 261 258 269 271

H 2O

H+(H2O)x x is pressure dependent H+(CH3OH)x x is pressure dependent C3H7+ C4H9+

697.1

166.5

980

234

761.6

181.9

917

219

751.5 820.2

179.5 195.9

1050 976

250 233

H+(NH3)x x is pressure dependent

854.1

204.0

825

197

CH3OH C 3H 8 i-C4H10 NH3


Comments General-purpose reagent gas

Significant signals observed for NO+ Most widely used reagent gas; usually used initially for most work; degree of fragmentation is relatively large; background spectrum is often large; can produce a large number of additional ions and quasimolecular ions Used for alcohols, ketones, esters, and amines

Uncommon reagent gas General-purpose reagent gas; fragmentation pattern is similar to that produced by ammonia


Negative Ion Reagent Gases for Chemical Ionization Mass Spectrometry Reagent Gas

Reactant Ion(s)

PA, kj/mol

PA, kcal/mol

HIA, kj/mol

HIA, kcal/mol

H2

H–

1675

400

72.9

17.4

NH3

NH2–

1691

404

75.4

18.0

N 2O

OH–

1637

391

177

42.2

CH3NO2

CH3O–

1595

381

152

36.2

O2 C2Cl3F3 (R-113) CH2Br2

O2– Cl–

1478 1394

353 333

42.3 349

10.1 83.4

Br–

1357

324

325

77.6


Comments H– ion is difficult to form in good yields; sometimes used for analysis of alcohols General-purpose gas, used for the analysis of esters Most common negative ion reagent gas used; often used as a mixture with N2O to eliminate O– signal; sometimes used as a N2O/He/N2O, 1:1:1 mixture; used with CH4 for simultaneous +/– ion work Almost as strong a base as OH–; used as a 1% mixture in CH4 Used in the analysis of alcohols Cl– is a weak Bronsted base useful for acidic compounds Br– is a weak Bronsted base (weaker than Cl–) that reacts with analytes that have a moderately acidic hydrogen


PROTON AFFINITIES OF SOME SIMPLE MOLECULES The following table gives the proton affinities (PA) of some simple molecules. For the occurrence of proton transfer (or reaction) between a reactant ion and a sample molecule, the reaction must be exothermic. Thus, ∆H (reaction) = PA (reactant gas) – PA (sample) < 0 The more exothermic the reaction, the greater the degree of fragmentation. Endothermic reactions do not yield a protonated form of a sample; therefore, the sample compound cannot be recorded. One can choose the proper reactant gas that will give the correct fragmentation pattern of a desired compound out of a mixture of compounds.1–3 Chapman3 lists positive ion chemical ionization applications by reagent gas and by compounds analyzed. The values are provided in kcal/mol for convenience; to convert to the appropriate SI unit (kJ/mol), multiply by 4.1845.

REFERENCES 1. Field, F.H., Chemical ionization mass spectrometry, Acc. Chem. Res., 1, 42, 1968. 2. Harrison, A.G., Chemical Ionization Mass Spectrometry, 2nd ed., CRC Press, Boca Raton, FL, 1992. 3. Chapman, J.R., Practical Organic Mass Spectrometry, 2nd ed., John Wiley & Sons, Chichester, U.K., 1995. Proton Affinities of Some Simple Molecules Family Alcohols Aldehydes Alkanes Alkenes Aromatics, substituted C6H5–G Amines

Carboxylic acids Dienes Esters Ethers Ketones Nitriles (cyano compounds) Sulfides Thiols

Typical Examples (PA in kcal/mol) CH3OH (184.9); CH3CH2OH (190.3); CH3CH2CH2OH (191.4); (CH3)3COH (195.0); CF3CH2OH (174.9) HCHO (177.2); CH3CHO (188.9); CH3CH2CHO (191.4); CH3CH2CH2CHO (193.3) CH4 (130.5); (CH3)3CH (195) H2C=CH2 (163.5); CH3CH=CH2 (184.9); (CH3)2C=CH2 (196.9); trans-CH3CH=CHCH3 (182.0) G=–H (182.8); –Cl (181.7); –F (181.5); –CH3 (191.2); –C2H5 (192.2); –CH2CH2CH3 (191.0); –CH(CH3)2 (191.4); –C(CH3)3 (191.6); –NO2 (193.8); –OH (196.2); –CN (196.3); –CHO (200.3); –OCH3 (200.6); –NH2 (211.5) 1°: NH3 (205.0); CH3NH2 (214.1); C2H5NH2 (217.1); CH3CH2CH2NH2 (218.5); CH3CH2CH2CH2NH2 (219.0) 2°: (CH3)2NH (220.5); (C2H5)2NH (225.1); (CH3CH2CH2)2NH (227.4) 3°: (CH3)3N (224.3); (C2H5)3N (231.2); (CH3CH2CH2)3N (233.4) HCO2H (182.8); CH3CO2H (190.7); CH3CH2CO2H (193.4); CF3CO2H (176.0) CH2=CHCH=CH2 (193); E–CH2=CHCH=CHCH3 (201.8); E–CH2=CHC(CH3)=CHCH3 (205.7); cyclopentadiene (200.0) HCO2CH3 (190.4); HCO2C2H5 (194.2); HCO2CH2CH2CH3 (195.2); CH3CO2CH3 (198.3); CH3CO2C2H5 (201.3); CH3CO2CH2CH2CH3 (202.0) (CH3)2O (193.1); (C2H5)2O (200.4); (CH3CH2CH2)2O (202.9); (CH3CH2CH2CH2)2O (203.9); tetrahydrofuran (199.6); tetrahydropyran (200.7) CH3COCH3 (197.2); CH3COC2H5 (199.4) HCN (178.9); CH3CN (190.9); C2H5CN (192.8); CH3CH2CH2CN (193.8) (CH3)2S (200.7); (C2H5)2S (205.6); [(CH3)2CH]2S (209.3) H2S (176.6); CH3SH (188.6); C2H5SH (192.0); [(CH3)2CH]2SH (194.7)



PROTON AFFINITIES OF SOME ANIONS The following table lists the proton affinities of some common anions (X–). Since the reaction of an anion (X–) with a proton (H+), X– + H+

H–X

is exothermic, it can be used to generate other anions that possess a smaller proton affinity value by the addition of the corresponding neutral species.1,2

REFERENCES 1. Chapman, J.R., Practical Organic Mass Spectrometry, 2nd ed., John Wiley & Sons, Chichester, U.K., 1995. 2. Harrison, A.G., Chemical Ionization Mass Spectrometry, 2nd ed., CRC Press, Boca Raton, FL, 1992.

Proton Affinities of Some Anions Anion NH2– H– OH– O·– CH3O– (CH3)2CHO– –CH CN 2 F– C5H5– O2·– CN– Cl–


Proton Affinity (kJ/mol) 1689 1676 1636 1595 1583 1565 1556 1554 1480 1465 1462 1395


DETECTION OF LEAKS IN MASS SPECTROMETER SYSTEMS The following tables provide guidance for troubleshooting possible leaks in the vacuum systems of mass spectrometers, especially those operating in electron impact mode. Leak testing is commonly done by playing a stream of a pure gas against a fitting, joint, or component that is suspected of being a leak source. If in fact the component is the source of a leak, one should be able to note the presence of the leak detection fluid on the mass spectrum. Here we present the mass spectra of methane tetrafluoride, 1,1,1,2-tetrafluoroethane (R-134a), n-butane, and acetone.1,2 Methane tetrafluoride, 1,1,1,2-tetrafluoroethane, and n-butane are handled as gases, while acetone is handled as a liquid. Typically, n-butane is dispensed from a disposable lighter, and acetone is dispensed from a dropper. Care must be taken when using acetone or a butane lighter for leak checking because of the flammability of these fluids.

REFERENCES 1. Bruno, T.J., CRC Handbook for the Analysis and Identification of Alternative Refrigerants, CRC Press, Boca Raton, FL, 1994. 2. NIST Chemistry Web Book, NIST Standard Reference Database 69, March 2003 release. Methane tetrafluoride 100. 69 Rel. abundance

80. 60. 40. 20.

50 31

0. 15.

30.

45.

60.

75.

90.

100.

120.

m/e 1,1,1,2-tetrafluoroethane 100.

33

69

83

Rel. abundance

80. 60. 40. 20.

51

0. 20.

40.

60.

80. m/e



Acetone 100. 43 Rel. abundance

80. 60.

58

40. 20. 0. 10.

20.

30.

40.

50.

60.

70.

m/e

Butane 100.

43

Rel. abundance

80. 60. 40.

27

29 41

20.

58

0. 10.

20.

30.

40. m/e


50.

60.


MASS RESOLUTION REQUIRED TO RESOLVE COMMON SPECTRAL INTERFERENCES ENCOUNTERED IN INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY The table below lists some common spectral interferences that are encountered in inductively coupled plasma mass spectrometry (ICP-MS), as well as the resolution that is necessary to analyze them.1 The resolution is presented as a dimensionless ratio. As an example, the relative molecular mass (RMM) of the polyatomic ion 15N16O+ would be 15.000108 + 15.994915 = 30.995023. This would interfere with 31P+ at a mass of 30.973762. The required resolution would be RMM/δRMM, or 30.973762/0.021261 = 1457. One should bear in mind that as resolution increases, the sensitivity decreases with subsequent effects on the price of the instrument. Note that small differences exist in the published exact masses of isotopes, but for the calculation of the required resolution, these differences are trivial. Moreover, recent instrumentation has provided rapid, high-resolution mass spectra with an uncertainty of less than 0.01%.

REFERENCES 1. Gregoire, D.C., Analysis of geological materials by inductively coupled plasma mass spectrometry, Spectrometry, 14, 14, 1999. Mass Resolution Required to Resolve Common Spectral Interferences Encountered in Inductively Coupled Plasma Mass Spectrometry Polyatomic Ion 14

N2+ N16O+ 40Ar12O+ 32S16O+ 35Cl16O+ 40Ar35Cl+ 40Ar + 2 15


Interfered Isotope (Natural Abundance %) 14

Si+ (92.21) P+ (100) 52Cr+ (83.76) 48Tl+ (73.94) 51V+ (99.76) 75As+ (100) 80Se+ (49.82) 31

Required Resolution 958 1457 2375 2519 2572 7775 9688


CHAPTER

11

Atomic Absorption Spectrometry

CONTENTS Introduction for Atomic Spectrometric Tables Standard Solutions: Selected Compounds and Procedures Limits of Detection Tables for Common Analytical Transitions in AES and AAS Detection Limits by Hydride Generation and Cold Vapor AAS Spectral Overlaps Relative Intensities of Elemental Transitions from Hollow Cathode Lamps Inert Gases Close Lines for Background Correction Beta Values for the Air–Acetylene and Nitrous Oxide–Acetylene Flames Lower-Energy-Level Populations (in Percent) as a Function of Temperature Critical Optimization Parameters for AES/AAS Methods Flame Temperatures and References on Temperature Measurements Fundamental Data for the Common Transitions Activated Carbon as a Trapping Sorbent for Trace Metals Reagent-Impregnated Resins as Trapping Sorbents for Trace Minerals Reagent-Impregnated Foams as Trapping Sorbents for Inorganic Species



INTRODUCTION FOR ATOMIC SPECTROMETRIC TABLES The tables presented in this section are designed to aid in the area of atomic spectrometric methods of analysis. The following conventions for abbreviation are recommended by the International Union of Pure and Applied Chemistry:1 Atomic emission spectrometry AES Atomic absorption spectrometry AAS Flame atomic emission spectrometry FAES Flame atomic absorption spectrometry FAAS Electrothermal atomic absorption spectrometry EAAS Inductively coupled plasma atomic emission spectrometry

ICP-AES

Other variations such as cold vapor and hydride generation are not abbreviated but spelled out, e.g., cold vapor AAS, hydride generation FAAS, etc. These abbreviations are used whenever appropriate throughout the section. Several of these tables have appeared in Parsons et al.’s Handbook2 in one form or another. They have been updated to the extent possible, and the wavelength values have been made to conform to those in the National Standard Reference Data System–National Bureau of Standards (NSRDS-NBS) 683 wherever possible. As several of the tables cite the same references, all cited references will be listed at the end of this introduction instead of being repeated at the end of each table. These tables were originally prepared by Parsons et al. for the first edition of this book.18

REFERENCES 1. Commission on spectrochemical and other optical procedures for analysis, nomenclature, symbols, units and their usage in spectrochemical analysis. I. General atomic emission spectroscopy. II. Data interpretation. III. Analytical flame spectroscopy and associated procedures, Spectrochim. Acta, 33B, 219, 1978. 2. Parsons, M.L., Smith, B.W., and Bentley, G.E., Handbook of Flame Spectroscopy, Plenum Press, New York, 1975. 3. Reader, J., Corliss, C.H., Weise, W.L., and Martin, G.A., Wavelengths and Transition Probabilities for Atoms and Atomic Ions, NSRDS-NBS 68, U.S. Government Printing Office, Washington, D.C., 1980. 4. Smith, B.W. and Parsons, M.L., Preparation of standard solutions: critically selected compounds, J. Chem. Educ., 50, 679, 1973. 5. Dean, J.A. and Rains, T.C., Standard solutions for flame spectrometry, in Flame Emission and Atomic Absorption Spectrometry, Vol. 2, Marcel Dekker, New York, 1971, p. 327. 6. Thermo Jarrell Ash Corp., Guide to Analytical Values for TJA Spectrometers, Thermo Jarrell Ash Corp., Waltham, MA, 1987. 7. Anderson, T.A. and Parsons, M.L., ICP emission spectra III: the spectra for the group IIIA elements and spectral interferences due to group IIA and IIIA elements, Appl. Spectrosc., 38, 625, 1984; Parsons, M.L., Forster, A., and Anderson, D., An Atlas of Spectral Interferences in ICP Spectroscopy, Plenum Press, New York, 1980. 8. Park, D.A., Further Investigations of Spectra and Spectral Interferences Due to Group A Elements in ICP Spectroscopy: Groups IVA and VA, Ph.D. thesis, Arizona State University, Tempe; Parsons, M.L., Unpublished data, Los Alamos National Laboratory, Los Alamos, NM, 1987. 9. Perkin-Elmer Corp., Mercury/Hydride System, Report 1876/6.79, Norwalk, CT, 1987. 10. Lovett, R.J., Welch, D.L., and Parsons, M.L., On the importance of spectral interferences in atomic absorption spectroscopy, Appl. Spectrosc., 29, 470, 1975. 11. Layman, L., Palmer, B., and Parsons, M.L., Unpublished data taken with the Los Alamos National Laboratory FTS Facility, Los Alamos, NM, 1987.



12. Sneddon, J., Background correction techniques in atomic spectroscopy, Spectroscopy, 2, 38, 1987. 13. Wittenberg, G.K., Haun, D.V., and Parsons, M.L., The use of free-energy minimization for calculating beta factors and equilibrium compositions in flame spectroscopy, Appl. Spectrosc., 33, 626, 1979. 14. Parsons, M.L., Smith, B.W., and McElfresh, P.M., On the selection of analysis lines in atomic absorption spectrometry, Appl. Spectrosc., 27, 471, 1973. 15. Parker, L.R., Jr., Morgan, S.L., and Deming, S.N., Simplex optimization of experimental factors in atomic absorption spectrometry, Appl. Spectrosc., 29, 429, 1975. 16. Parsons, M.L. and Winefordner, J.D., Optimization of the critical instrumental parameters for achieving maximum sensitivity and precision in flame-spectrometric methods of analysis, Appl. Spectrosc., 21, 368, 1967. 17. Wiese, W.L., Smith, M.W., and Glennon, B.M., Atomic Transition Probabilities, Vol. I, Hydrogen through Neon, NSRDS-NBS 4, U.S. Government Printing Office, Washington, D.C., 1966. 18. Bruno, T.J. and Svoronos, P.D.N., CRC Handbook of Basic Tables for Chemical Analysis, CRC Press, Boca Raton, FL 1989.



STANDARD SOLUTIONS: SELECTED COMPOUNDS AND PROCEDURES The compounds selected for this table were chosen using a rather stringent set of criteria, including stability, purity, ease of preparation, availability, high molecular mass, and toxicity. It is very important to have a compound that is pure and can be dried, weighed, and dissolved with comparative ease. The list of compounds provided here meets those goals as much as possible. No attempt was made to include all compounds that meet these criteria, nor are the compounds in this list trivial to dissolve; some require a rather long time and vigorous conditions. In this table the significant figures in all columns represent the accuracy with which the atomic masses of the elements are known. This table was compiled from References 4 and 5. Standard Solutions: Selected Compounds and Procedures

Element

Compound

Aluminum Antimony

Al–metal KSbOC4H4O6 ⋅1/2 H2O Sb–metal As2O3 BaCO3 BaCl2 Be–metal BeSO4 ⋅ 4H2O Bi2O3 Bi–metal H3BO3 KBr CdO Cd–metal CaCO3 (NH4)2Ce(NO3)4 Cs2SO4 NaCl K2Cr2O7 Cr–metal Co–metal Cu–metal CuO CuSO4⋅5H2O Dy2O3 Er2O3 Eu2O3 NaF Gd2O3 Ga–metal GeO2

Arsenic Barium Beryllium Bismuth Boron Bromine Cadmium Calcium Cerium Cesium Chlorine Chromium Cobalt Copper

Dysprosium Erbium Europium Fluorine Gadolinium Gallium Germanium

Gold Hafnium Holmium Indium Iodine Iridium Iron

Au–metal Hf–metal Ho2O3 In2O3 In–metal KIO3 Na3IrCl6 Fe–metal


Relative Formula Mass 26.982 324.92

Weight for 1000 µg/l (PPM)-g/l

Solvent

1.0000 Hot dil. HCl–2 M 2.6687 Water (antimony potassium tartarate) 121.75 1.0000 Hot aq. reg. 197.84 1.3203 1:1 NH3 197.35 1.4369 Dil. HCl 208.25 1.5163 Water 9.0122 1.0000 HCl 177⋅135 19.6550 Water + acid 465.96 1.1148 HNO3 208.980 1.00000 HNO3 61.84 5.720 Water 119.01 1.4894 Water 128.40 1.1423 HNO3 112.40 1.0000 Dil. HCl 100.09 2.4972 Dil. HCl 548.23 3.9126 Water 361.87 1.3614 Water 58.442 1.6485 Water 294.19 2.8290 Water 51.996 1.0000 HCl 58.933 1.0000 HNO3 63.546 1.0000 Dil. HNO3 69.545 1.2517 Hot HCl 249.678 3.92909 Water 373.00 1.477 Hot HCl 382.56 1.1435 Hot HCl 351.92 1.1579 Hot HCl 41.988 2.2101 Water 362.50 1.1526 Hot HCl 69.72 1.000 Hot HNO3 104.60 1.4410 Hot 1 M NaOH or 50 g oxalic acid + water 196.97 1.0000 Hot aq. reg. 178.49 1.0000 Hf, Fusion 377.86 1.1455 Hot HCl 277.64 1.2090 Hot HCl 114.82 1.0000 Dil. HCl 214.00 1.6863 Water 473.8 2.466 Water 55.847 1.0000 Hot HCl

Note APS d

PS,a NIST f d a g

PS, NISTk APS

f

PS PS, NIST APS APS APS c c c h c i

APS, NIST j c

PS APS


Standard Solutions: Selected Compounds and Procedures (continued)

Element Lanthanum Lead Lithium Lutetium Magnesium Manganese Mercury Molybdenum Neodymium Nickel Niobium Osmium Palladium Phosphorus Platinum Potassium

Praseodymium Rhenium Rhodium Rubidium Ruthenium Samarium Scandium Selenium Silicon Silver Sodium

Strontium Sulfur Tantalum Tellurium Terbium Thallium Thorium Thulium Tin Titanium

Compound La2O3 Pb(NO3)2 Li2CO3 Lu2O3 MgO Mg–metal MnSO4⋅H2O HgCl2 Hg–metal MoO3

Relative Formula Mass


325.82 331.20 73.890 397.94 40.311 24.312 169.01 271.50 200.59 143.94

1.1728 1.5985 5.3243 1.1372 1.6581 1.0000 3.0764 1.3535 1.0000 1.5003

Nd2O3 336.48 Ni–metal 58.71 Nb2O5 265.81 Nb–metal 92.906 Os–metal 190.20 Pd–metal 106.40 KH2PO4 136.09 (NH3)2HPO4 209.997 K2PtCl4 415.12 Pt–metal 195.05 KCl 74.555 KHC6H4O4 204.22 (potassium hydrogen phthalate) 294.19 K2Cr2O7 Pr6O11 1021.43 186.2 Re–metal 289.3 KReO4 Rh–metal 102.91 Rb2SO4 267.00 RuO4 165.07 Sm2O3 348.70 Sc2O3 137.91 Se–metal 78.96 SeO2 110.9 28.086 Si–metal 60.085 SiO2 AgNO3 169.875 Ag–metal 107.870 NaCl 58.442 Na2C2O4 134.000 (sodium oxalate) SrCO3 147.63 174.27 K2SO4 (NH4)2SO4 114.10 Ta2O5 441.893 Ta–metal 180.948 159.60 TeO2 Tb2O3 365.85 Tl2CO3 468.75 TlNO3 266.37 Th(NO3)4 552.118 ⋅4H2O Tm2O3 385.87 Sn–metal 118.69 SnO 134.69 Ti–metal 47.90


Solvent

Note c APS, NIST APSf c

1.1664 1.000 1.4305 1.0000 1.0000 1.0000 4.3937 6.77983 2.1278 1.0000 1.9067 5.2228

Hot HCl HCl Dil. HCl Hot HCl HCl Dil. HCl Water Water 5 M HNO3 1 M NaOH or 2 M HN3 HCl Hot HNO3 HF, fusion HF + H2SO4 Hot H2SO4 Hot HNO3 Water Water Water Hot aq. reg. Water Water

3.7618 1.20816 1.000 1.554 1.0000 1.5628 1.6332 2.3193 1.5339 1.000 1.405 1.0000 2.1393 1.57481 1.0000 2.5428 2.91432

Water HCl HNO3 Water Hot H2SO4 Water Water Hot HCl Hot HCl Hot HNO3 Water NaOH, conc. HF Water HNO3 Water Water

PS, NIST c

1.6849 5.4351 3.5585 1.22130 1.0000 1.2507 1.1512 1.1468 1.3034 2.37943

Dil. HCl Water Water HF, fusion HF + H2SO4 HCl Hot HCl Water Water HNO3

APSf

1.1421 1.0000 1.1348 1.000

Hot HCl HCl HCl 1:1 H2SO4

c

m a

c APS m, o o b

APS, NIST PS, NIST PS, NIST

c

APSp PS PS, NIST

n, o o c APSa

APS


Standard Solutions: Selected Compounds and Procedures (continued)

Element

Compound

Tungsten

Na2WO4⋅2H2O Na2WO4 UO2 U 3O 6 UO2(NO3)2⋅6H2O V 2O 5 NH4VO3 Yb2O3 Y 2O 3 ZnO Zn–metal Zr–metal ZrOCl2⋅8H2O

Uranium

Vanadium Ytterbium Yttrium Zinc Zirconium

Relative Formula Mass 329.86 293.83 270.03 842.09 502.13 181.88 116.98 394.08 225.81 81.37 65.37 91.22 322.2


Solvent

1.7942 1.5982 1.1344 1.1792 2.1095 1.78521 2.2963 1.1386 1.2700 1.245 1.000 1.000 3.533

Water Water HNO3 HNO3 Water Hot HCl Dil. HNO3 Hot HCl Hot HCl HCl HCl HF, fusion HCl

Note q d PS, NIST

c c APS APS, NIST j

Note: PS = primary standard; APS = compounds that approach primary standard quality; NIST = compounds sold as primary standards by the NIST Standard Reference Materials Program, 100 Bureau Drive, Gaithersburg, MD 20899-3460 (www.nist.gov). a

Highly toxic. Very highly toxic. c The rare earth oxides, because they absorb CO and water vapor from the atmosphere, should be 2 freshly ignited prior to weighing. d Loses water at 110°C. Water is only slowly regained, but rapid weighing and desiccator storage are required. e Drying at 250°C, rapid weighing, and desiccator storage are required. f Add a quantity of water, then add dilute acid and swirl until the CO has ceased to bubble out, and 2 then dilute. g Dissolve in water, then add 5 ml of concentrated HCl and dilute. h Sodium fluoride solutions will etch glass and should be freshly prepared. i Because the melting point is 29.6°C, the metal may be warmed and weighed as a liquid. j Zr and Hf compounds were not investigated in the laboratory of reference 5. k Boric acid may be weighed directly from the bottle. It loses 1 H O at 100°C, but it is difficult to dry 2 to a constant mass. l Several references suggest that the addition of acid will help stabilize the solution. m This compound may be dried at 100°C without losing the water of hydration. n Nb and Ta are slowly soluble in 40% HF. The addition of H SO accelerates the dissolution process. 2 4 o Dissolve in 20 ml of hot HF in a platinum dish, add 40 ml of H SO and evaporate to fumes, and 2 4 dilute with 8 M H2SO4. p When kept dry, silver nitrate crystals are not affected by light. Solutions should be stored in brown bottles. q Sodium tungstate loses both water molecules at 110°C. The water is not rapidly regained, but the compound should be kept in a desiccator after drying and should be weighed quickly once it is removed. b



LIMITS OF DETECTION TABLES FOR COMMON ANALYTICAL TRANSITIONS IN AES AND AAS The following five tables present the common transitions for analysis and the detection limits for AES and AAS on the basis of source, where appropriate for the specific atom cell indicated. The detection limits are from the literature cited and are given in parts per billion (ppb) or nanograms per milliliter of aqueous solution. The limits of detection (LODs) are generally defined as a signal to noise of two or three. This generally relates to a concentration that produces a signal of two or three times the standard deviation of the measurement. These are measured in dilute aqueous solution and represent the best that the system was capable of measuring. In most cases, the detection limit in real samples will be one or two orders of magnitude higher, or worse, than those stated here. The type designation is I for free atom and II for single ion. In all cases, NO means that no observation was made for the situation indicated, and NA means that either AES or AAS was observed but no detection limit was reported. In all cases where possible, the wavelengths of the transitions were made to conform with Reference 3; any wavelength below 200 nm is the wavelength given in vacuum; all others are in air.



Limits of Detection for the Air–Hydrocarbon Flamea Element

Symbol

Antimony

Sb

Bismuth Calcium Cesium

Bi Ca Cs

Chromium Cobalt Copper

Cr Co Cu

Gallium Gold Indium Iridium

Ga Au In Ir

Iron Lead Lithium Magnesium Manganese

Fe Pb Li Mg Mn

Mercury Molybdenum Nickel Osmium Palladium

Hg Mo Ni Os Pd

Platinum Potassium Rhodium Rubidium

Pt K Rh Rb

Ruthenium

Ru

Selenium

Se

Silver

Ag

Sodium

Na

Strontium

Sr

Tellurium Thallium

Te Tl

Tin Zinc

Sn Zn

Wavelength (nm) 217.581 231.147 223.061 22.673 455.5276 852.1122 357.869 240.725 324.754 327.396 287.424 242.795 303.936 208.882 2639.71 248.3271 283.3053 670.776 285.213 279.482 403.076 253.652 313.259 232.003 290.906 244.791 247.642 265.945 766.490 343.489 420.180 780.027 349.894 372.803 196.09 203.98 328.068 338.289 330.237 588.9950 589.5924 407.771 460.733 214.281 276.787 377.572 224.605 213.856

Type I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I

LOD-AAS (ppb) 100 100 50 2 600 50 5 5 50 50 70 20 50 15,000 2000 5 10 5 0.3 2 2 500 30 5 17,000 2000 30 100 5 30 NA 5 300 3000 100 2000 5 200 NA 2 2 NA 10 100 30 2400 30 2

Note: These data were taken from Reference 2. a Flames formed from air combined with the lighter hydrocarbons, such as methane, propane, butane, or natural gas, behave in a very similar fashion with similar temperatures, similar chemical properties, etc.



Limits of Detection for the Air–Acetylene Flame Element

Symbol

Aluminum

Al

Antimony

Sb

Arsenic Barium

As Ba

Bismuth Boron Cadmium

Bi B Cd

Calcium

Ca

Cesium

Cs

Chromium

Cr

Cobalt

Co

Copper

Cu

Gallium

Ga

Germanium Gold

Ge Au

Indium

In

Iodine

I

Iridium

Ir

Iron

Fe

Lead

Pb

Lithium

Li

Magnesium

Mg

Manganese

Mn

Mercury Molybdenum

Hg Mo

Nickel

Ni

Niobium Osmium

Nb Os


Wavelength (nm) 308.2153 309.2710 396.1520 206.833 217.581 231.147 259.805 193.759 455.403 553.548 223.061 249.677 228.8022 326.1055 393.366 396.847 422.673 455.5276 852.1122 357.869 425.435 240.725 352.685 324.754 327.396 287.424 294.364 417.204 265.1172 242.795 267.595 303.936 325.609 451.131 183.038 206.163 208.882 2639.71 248.3271 371.9935 217.000 283.3053 368.3462 670.776 451.857 279.553 280.270 285.213 279.482 403.076 253.652 313.259 379.825 390.296 232.003 352.454 309.418 290.906

Type

LOD-AES (ppb)

LOS-AAS (ppb)

I I I I I I I I II I I I I I II II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II II I I I I I I I I I II I

NO NO NA NA NA 3000 NA 10,000 NA NA 3000 NA 500 NA NO NO 0.5 NA NA NA NA NO NA NA NA NO NA NA 7000 NA NA NA NA NA NO 2,500,000 NO NO NO NA NO NA NA NA NO NO NO NA NA NA NA NO 80,000 100 NO NA NO NA

700 500 600 50 40 40 NO 140 NO NO 25 NO 1 NA 5000 5000 0.5 NO 8 3 200 4 125 1 120 50 50 1500 6 90 30 20 200 8000 NO 600 2500 5 700 9 240 NO 0.3 NA NA NA 0.1 2 600 140 20 900 1600 2 350 NA 1200


Limits of Detection for the Air–Acetylene Flame (continued) Element

Symbol

Palladium

Pd

Phosphorus Platinum

P Pt

Potassium Rhenium Rhodium

K Re Rh

Rubidium

Rb

Ruthenium

Ru

Selenium

Se

Silver

Ag

Sodium

Na

Strontium

Sr

Sulfur Tellurium

S Te

Thallium

Tl

Tin

Sn

Tungsten

W

Uranium Vanadium

U V

Ytterbium Zinc Zirconium

Yb Zn Zr

Wavelength (nm) 244.791 247.642 340.458 363.470 213.547 214.423 265.945 766.490 346.046 343.489 369.236 420.180 780.027 349.894 372.803 196.09 203.98 328.068 338.289 330.237 588.9950 589.5924 407.771 421.552 460.733 180.7311 214.281 238.578 276.787 377.572 535.046 224.605 235.484 283.999 326.234 255.135 400.875 591.539 318.540 437.924 398.799 213.856 351.960

Type

LOD-AES (ppb)

LOS-AAS (ppb)

I I I I I I I I I I I I I I I I I I I I I I II II I I I I I I I I I I I I I I I I I I I

NO NO NA NA NO NO NA NA NO NA NA NA NA NA NA NA 50,000 NA NA NO NA NA NA NO NA NO 500 NO NA NA NA NO 2000 NA NA 90,000

20 20 660 300 30,000 350 50 1 800 2 70 NO 0.3 400 250 50 10,000 1 70 NA 1 0.2 400 NA 2 30,000 30 NA 30 1200 12,000 10 600 1000 NO 3000

NA NA 300 NO 7000 NO

NO NO NO 80 1 NA

Note: These data were taken from References 2 and 6.



Limits of Detection for the Nitrous Oxide–Acetylene Flame Element

Symbol

Wavelength (nm)

Type

LOD-AES (ppb)

LOD-AAS (ppb)

Aluminum

Al

Barium Beryllium Boron

Ba Be B

Cadmium Calcium Cesium

Cd Ca Cs

Chromium Cobalt Copper

Cr Co Cu

Dysprosium

Dy

Erbium

Er

Europium Gadolinium

Eu Gd

Gallium Germanium Gold Hafnium Holmium

Ga Ge Au Hf Ho

Indium

In

Iridium Iron Lanthanum

Ir Fe La

Lead Lithium Lutetium

Pb Li Lu

Magnesium Manganese Mercury Molybdenum

Mg Mn Hg Mo

Neodymium

Nd Ni Nb

Osmium

Os

Palladium Phosphorus

Pd P

Platinum

Pt

I I I I I I I I I I I I I I I I I II I I II I I I I I I I I II I I I I I I I II I I I II I I I I I I I I I I I I I I I I I I

NA NA 3 1 100 NO NO NO NO 800 0.1 600 0.02 1 200 30 3 NO 20 NO NO 20 0.2 NO 1000 5 400 500 NO NO 10 NO NO NO 1 NO 10 NO 4000 0.2 0.001 NO 400 1 1 10,000 10 300 10 200

Nickel Niobium

308.2153 309.2710 396.1520 553.548 234.861 208.891 208.957 249.677 249.773 326.1055 422.673 455.5276 852.1122 425.435 352.685 324.754 327.396 353.170 404.597 421.172 337.271 400.796 459.403 368.413 440.186 417.204 265.1172 267.595 307.288 345.600 405.393 410.384 303.936 325.609 451.131 208.882 371.9935 408.672 550.134 368.3462 670.776 261.542 451.857 285.213 403.076 253.652 313.259 379.825 390.296 463.424 492.453 352.454 334.906 405.894 290.906 442.047 363.470 177.499 213.547 265.945

NO 20 900 8 1 NA 24,000 700 1500 NO 1 NO NO NO NO NO NO 800 500 50 100 40 30 2000 NO NO 50 NO 2000 3000 400 40 1000 700 3500 500 NO 7500 2000 NO NO 3000 NO NO NO NO 25 NO NO 600 700 NO 1000 5000 80 NA NO 30,000 29,000 2000


20 NO 60 NO 2000 40 NO NO 2000


Limits of Detection for the Nitrous Oxide–Acetylene Flame (continued) Element

Symbol

Wavelength (nm)

Type

LOD-AES (ppb)

LOD-AAS (ppb)

Potassium Praseodymium Rhenium Rhodium

K Pr Re Rh

Rubidium Ruthenium Samarium

Rb Ru Sm

Scandium Selenium Silicon

Sc Se Si

Silver Sodium

Ag Na

Strontium Tantalum

Sr Ta

Terbium Thallium

Tb Tl Th

Thulium Tin

Tm Sn

Titanium

Ti

Tungsten

W

Uranium Vanadium

U V

Ytterbium Yttrium Zinc Zirconium

Yb Y Zn Zr

I I I I I I I I I I I I I I I I I I I I I I I II I I I I II I I I I I I I I I I I I

0.01 500 200 NO 10 8 300 NO 50 10 100,000 3000 NO 2 0.01 0.01 0.1 NO 4000 NA 50 2 NO 10,000 4 NO NO 100 NO NA 30 NO 200 NO 200 7 0.2 NO 10,000 1200 3000

NO 2000 200 700 1400 NO NO 500 14,000 20 NO 20 NA NO NO NO 50 800 NO 600 NO

Thorium

766.490 495.137 364.046 343.489 369.236 780.027 372.803 429.674 476.027 391.181 196.09 251.6113 288.1579 328.068 588.9950 589.5924 469.733 271.467 474.016 432.643 377.572 535.046 324.4448 491.9816 371.791 224.605 235.484 283.999 334.941 364.268 365.350 255.135 400.875 358.488 318.540 437.924 398.799 410.238 213.856 351.960 360.119

Note: These data were taken from References 2 and 6.


181,000 NO 10 3000 90 NO NA 10 500 500 7500 7000 20 100 5 50 NO NO 1000


Limits of Detection for Graphite Furnace AASa Element

Symbol

Wavelength (nm)

Type

LOD (ppb)

Aluminum

Al

Antimony

Sb

Arsenic

As

Barium Beryllium Bismuth Cadmium Calcium Chromium Cobalt Copper

Ba Be Bi Cd Ca Cr Co Cu

Erbium Gadolinium Gallium Germanium Gold Holmium

Er Gd Ga Ge Au Ho

Indium Iodine Iridium Iron

In I Ir Fe

Lanthanum Lead

La Pb

Lithium Magnesium Manganese

Li Mg Mn

Mercury Molybdenum Nickel Osmium Palladium Phosphorus

Hg Mo Ni Os Pd P

Platinum Potassium Rhenium Rhodium Rubidium Selenium Silicon Silver Sodium Strontium Sulfur

Pt K Re Rh Rb Se Si Ag Na Sr S

I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I

Tellurium Thallium

Te Tl

308.2153 309.2710 396.1520 206.833 217.581 231.147 189.042 193.759 553.548 234.861 223.061 228.8022 422.673 357.869 240.725 324.754 327.396 400.796 440.186 287.424 265.1172 242.795 345.600 405.393 303.936 183.038 208.882 248.3271 371.9935 550.134 217.000 283.3053 670.776 285.213 279.482 403.076 253.652 313.259 232.003 290.906 247.642 177.499 213.547 253.561 265.945 766.490 346.046 343.489 780.027 196.09 251.6113 328.068 588.9950 460.733 180.7311 182.0343 216.89 214.281 276.787

NA 0.01 600 NA 0.08 NA NA 0.12 0.04 0.003 0.01 0.0002 0.01 0.004 8 0.005 NA 0.3 0.3 0.01 0.1 0.01 NA NA 0.02 40,000 0.5 0.01 NA 0.5 0.007 NA 0.01 0.0002 0.0005 NA 0.2 0.03 0.05 2 0.05 NA 20 NA 0.2 0.004 10 0.1 NA 0.05 0.6 0.001 0.004 0.01 NA NA NA 0.03 0.01


I I


Limits of Detection for Graphite Furnace AASa (continued) Element

Symbol

Wavelength (nm)

Type

LOD (ppb)

Tin

Sn

Titanium

Ti

Uranium Vanadium Ytterbium Yttrium Zinc

U V Yb Y Zn

235.484 283.999 364.268 365.350 358.488 318.540 398.799 410.238 213.856

I I I I I I I I I

0.03 NA 0.3 NA 30 0.4 0.01 10 0.001

a

The detection limits for the graphite furnace AAS are calculated using 100 µl of sample. In graphite furnace AAS, additional chemicals are often added to aid in determining certain elements. Walter Slavin has published an excellent guide to these issues and has provided an excellent bibliography: Slavin, W., Graphite Furnace Source Book, PerkinElmer Corp., Ridgefield, CT, 1984; and Slavin, W. and Manning, D.C., Furnace interferences, a guide to the literature, Prog. Anal. Spectrosc., 5, 243, 1982.

Limits of Detection for ICP-AES Element

Symbol

Wavelength (nm)

Type

LOD (ppb)

Reference

Aluminum

Al

Antimony

Sb

Arsenic

As

Barium

Ba

Beryllium

Be

Bismuth

Bi

Boron

B

Bromine

Br

Cadmium

Cd

Calcium

Ca

Carbon

C

Cerium

Ce

167.0787 308.2153 309.2710 396.1520 206.833 217.581 231.147 259.805 189.042 193.759 197.262 234.984 455.403 493.409 553.548 234.861 313.042 313.107 223.061 289.798 208.891 208.957 249.677 249.773 470.486 827.244 214.441 226.502 228.8022 326.1055 364.441 393.366 396.847 422.673 193.0905 247.856 394.275 413.765 418.660

II I I I I I I I I I I I II II I I II II I I I I I I II I II II I I I II II I I I II II II

1 0.4 0.02 0.2 10 15 61 107 136 2 76 90 0.001 0.3 2 0.003 0.1 0.01 0.03 10 5 3 0.1 2 NA NA 0.1 0.05 0.08 3 0.5 0.0001 0.002 0.2 40 100 2 40 0.4

6 7 8 7 7 7 7 7 8 7 7 7 8 7 7 7 6 8 8 7 8 8 8 8 8 8 8 8 8 8 8 8 8 8 6 8 8 6 7



Limits of Detection for ICP-AES (continued) Element

Symbol

Wavelength (nm)

Type

LOD (ppb)

Reference

Chlorine

Cl

Chromium

Cr

Cobalt

Co

Copper

Cu

Dysprosium Erbium

Dy Er

Europium Fluorine Gadolinium Gallium

Eu F Gd Ga

Germanium

Ge

Gold

Au

Hafnium

Hf

Holmium

Ho

Hydrogen

H

Indium

In

Iodine

I

Iridium

Ir

Iron

Fe

Lanthanum

La

Lead

Pb

Lithium Lutetium

Li Lu

Magnesium

Mg

Manganese

Mn

Mercury

Hg

413.250 837.594 205.552 267.716 357.869 425.435 228.615 238.892 213.5981 324.754 327.396 353.170 337.271 400.796 381.967 685.603 342.247 287.424 294.364 417.204 199.8887 209.4258 265.1172 242.795 267.595 277.336 339.980 345.600 389.102 486.133 656.2852 230.605 303.936 325.609 451.131 183.038 206.163 224.268 2639.71 238.204 259.9396 371.9935 333.749 408.672 217.000 220.3534 283.3053 368.2462 670.776 261.542 451.857 279.553 280.270 285.231 257.610 403.076 184.905 194.227 253.652

II I II II I I II II II I I II II I II I II I I I I I I I I II II II II I I II I I I I I II I II II I II II I II I I I II I II II I II I II II I

NA NA 0.009 0.08 0.1 5 0.3 0.1 7 0.01 0.06 1 1 1 0.06 NA 0.4 78 3 0.6 0.6 11 4 2 0.9 2 5 1 0.9 NA NA 30 15 15 30 NA 10 0.6 0.6 0.004 0.09 0.3 2 0.1 30 0.6 2 20 0.02 0.1 8 0.003 0.01 0.2 0.01 0.6 1 10 1

7 8 8 8 8 8 8 7 8 8 8 8 8 7 7 8 7 7 8 8 8 8 7 8 7 8 6 6 8 8 7 8 8 6 7 7 8 8 8 8 7 7 6 8 8 8 7 8 7 7 7 7 7 7 7 7 7 6 7




Symbol

Wavelength (nm)

Type

LOD (ppb)

Reference

Molybdenum

Mo

Neodymium Nickel

Nd Ni

Niobium Nitrogen

Nb N

Osmium

Os

Oxygen

O

Palladium

Pd

Phosphorus

P

Platinum

Pt

Potassium Praseodymium

K Pr

Rhenium

Re

Rhodium

Rh

Rubidium

Rb

Ruthenium

Ru

Samarium

Sm

Scandium Selenium

Sc Se

Silicon

Si

Silver

Ag

Sodium

Na

Strontium

Sr

Sulfur

S

II I I I II II I I II I I II I I I I I I I I I I I II II ? II II I I I I II I I II II II I I I I I I I I I II II I I I

Tantalum

Ta

Tellurium

Te

Terbium

Tb

202.030 313.259 379.825 390.296 401.225 221.648 232.003 352.454 309.418 174.2729 821.634 225.585 290.906 426.825 777.194 340.458 363.470 177.499 213.547 253.561 214.423 265.945 766.490 390.805 422.535 197.3 221.426 233.477 343.489 369.236 420.180 780.027 240.272 349.894 372.803 359.260 373.912 361.384 196.09 203.98 251.6113 288.1579 328.068 338.289 330.237 588.9950 589.5924 407.771 421.552 460.733 180.7311 182.0343 216.89 226.230 240.063 296.513 214.281 238.578 350.917 367.635

0.3 NA 0.2 80 0.3 2 6 0.2 0.2 1000 27,000 4 6 NA NA 2 1 NA 16 15 16 0.9 5 0.3 10 6 4 30 8 7 38,000 100 8 NA 60 0.5 2 0.1 0.1 0.03 2 10 0.8 7 100 0.1 0.5 0.2 0.1 0.4 15 30 NA 15 13 5 0.7 2 0.1 1.5

8 8 7 8 7 8 8 7 7 8 8 8 8 8 8 8 8 8 6 7 6 7 8 8 7 7 6 7 6 8 8 6 6 8 7 8 7 8 8 8 7 7 8 8 8 7 8 6 8 8 6 7 7 8 6 7 8 8 7 8


II II II I I II II



Symbol

Wavelength (nm)

Type

LOD (ppb)

Reference

Thallium

Tl

Thorium

Th

Thulium

Tm

Tin

Sn

Titanium

Ti

Tungsten

W

Uranium

U

Vanadium

V

Ytterbium

Yb

Yttrium

Y

Zinc

Zn

Zirconium

Zr

190.864 276.787 377.572 283.7295 401.9129 313.126 346.220 189.991 235.484 283.999 326.234 334.941 365.350 368.520 207.911 276.427 400.875 263.553 385.957 309.311 311.062 437.924 328.937 369.419 371.030 377.433 202.548 213.856 343.823

II I I II II II II II I I I II I II II II I II II II II I II II II II II I II

4 27 17 8 1.3 0.9 0.2 0.05 9 10 0.5 0.1 230 0.2 7 0.8 3 70 2 0.06 0.06 0.2 0.01 0.02 0.04 0.1 0.6 0.07 0.06

8 6 8 6 8 6 7 8 8 8 8 8 8 8 8 7 7 6 7 7 7 7 8 7 7 8 8 8 7



DETECTION LIMITS BY HYDRIDE GENERATION AND COLD VAPOR AAS In addition to the AAS methods in flames or graphite furnaces, the elements listed below are detected and determined at extreme sensitivity by introduction into a flame or a hot quartz cell by AAS. Detection Limits by Hydride Generation and Cold Vapor AAS Element Antimony, Sb Arsenic, As Bismuth, Bi Mercury, Hg Selenium, Se Tellurium, Te Tin, Sn

Wavelengtha (nm) 217.581 193.759 223.061 313.652 196.09 214.281 235.484

LODb (ppb) 0.1 0.02 0.02 0.02 0.02 0.02 0.5

Note: These data were taken from Reference 9. a It has been assumed that the transitions used for these detection limits were the most sensitive cited for AAS. b The detection limits are based on 50-ml sample solution volumes.



SPECTRAL OVERLAPS In FAES and FAAS, the analytical results will be totally degraded if there is a spectral overlap of an analyte transition. This can result from an interfering matrix element with a transition close to that of the analyte. This table presents a list of those overlaps that have been observed and those that are predicted to happen. In many cases the interferant element has been present in great excess when compared to the analyte species. Therefore, if the predicted interferant element is a major component of the matrix, a careful investigation for spectral overlap should be made. Excitation sources other than flames were not covered in this study. Spectral Overlaps Analyte Element

Wavelength (nm)

Interfering Element

Observed Overlaps Vanadium Lead Nickel Arsenic

Wavelength (nm)

Aluminum Antimony Antimony Cadmium

308.2153 217.023 231.147 228.8022

Calcium Cobalt Copper Gallium

422.673 252.136 324.754 403.299

Germanium Indium Europium Manganese

422.6562 252.137 324.755 403.307

Iron Manganese Mercury Silicon Zinc

271.9027 403.307 253.652 250.690 213.856

Platinum Gallium Cobalt Vanadium Iron

271.904 403.299 253.649 250.690 213.859

Boron Bismuth Cobalt Cobalt

249.773 202.121 227.449 242.493

Cobalt Cobalt Cobalt Cobalt

252.136 346.580 350.228 351.348

Tungsten Iron Rhodium Iridium

252.132 346.5860 350.252 351.364

Copper Gallium Gold Hafnium

216.509 294.417 242.795 295.068

Platinum Tungsten Strontium Niobium

216.517 294.440 242.810 295.088

Hafnium Indium Iridium Iridium

302.053 303.936 208.882 248.118

Iron Germanium Boron Tungsten

302.0639 303.9067 208.891 248.144

Iron Lanthanum Lead Molybdenum

248.3271 370.454 261.3655 379.825

Tin Vanadium Tungsten Niobium

248.339 370.470 261.382 379.812

Osmium Osmium Osmium Osmium

247.684 264.411 271.464 285.076

Nickel Titanium Tantalum Tantalum

247.687 264.426 271.467 285.098


Predicted Overlaps Germanium Gold Rhenium Osmium

308.211 217.000 231.096 228.812

249.7962 202.138 227.462 242.497


Spectral Overlaps (continued) Analyte Element

Wavelength (nm)

Interfering Element

Wavelength (nm)

Osmium Palladium Platinum Rhodium

301.804 363.470 227.438 350.252

Hafnium Ruthenium Cobalt Cobalt

301.831 363.493 227.449 350.262

Scandium Scandium Scandium Silicon

298.075 298.895 393.338 252.4108

Hafnium Ruthenium Calcium Iron

298.081 298.895 393.366 252.4293

Silver Strontium Tantalum Tantalum

328.068 421.552 263.690 266.189

Rhodium Rubidium Osmium Iridium

328.055 421.553 263.713 266.198

Tantalum Thallium Thallium Tin

269.131 291.832 377.572 226.891

Germanium Hafnium Nickel Aluminum

269.1341 291.858 377.557 226.910

Tin Tin Titanium Tungsten

266.124 270.651 264.664 265.654

Tantalum Scandium Platinum Tantalum

266.134 270.677 264.689 265.661

Tungsten Vanadium Zirconium Zirconium Zirconium

271.891 252.622 301.175 386.387 396.826

Iron Tantalum Nickel Molybdenum Calcium

271.9027 252.635 301.200 386.411 396.847

Note: These data were taken from Reference 10.



RELATIVE INTENSITIES OF ELEMENTAL TRANSITIONS FROM HOLLOW CATHODE LAMPS In AAS the hollow cathode lamp (HCL) is the most important excitation source for most of the elements determined. However, sufficient light must reach the detector for the measurement to be made with good precision and detection limits. For elements in this table with intensities of less than 100, HCLs are probably inadequate, and other sources such as electrodeless discharge lamps should be investigated. Relative Intensities of Elemental Transitions from Hollow Cathode Lamps Element

Fill Gas

Aluminum

Ne

Antimony

Ne

Arsenic

Ar

Barium

Ne

Beryllium Bismuth

Ne Ne

Boron Cadmium

Ar Ne

Calcium Cerium

Ne Ne

Chromium

Ne

Cobalt

Ne

Copper

Ne

Dysprosium

Ne

Erbium

Ne

Europium

Ne

Gadolinium

Ne

Gallium

Ne

Germanium

Ne

Gold

Ne

Hafnium

Ne


Wavelength (nm) 309.2710 309.2839 } 396.1520 217.581 231.147 193.759 197.262 553.548 350.111 234.861 223.061 306.772 249.773 228.8022 326.1055 422.673 520.012 520.042 } 569.699 357.869 425.435 240.725 345.350 352.685 324.754 327.396 404.597 418.682 421.172 400.796 386.285 459.403 462.722 368.413 407.870 287.424 417.204 265.1172 265.1568 } 259.2534 242.795 267.595 307.288 286.637

Relative Emission Intensitya 1200 800 250 250 125 125 400 200 2500 120 400 400 2500 5000 1400 8 8 6000 5000 1000 1500 1300 7000 6000 2000 2000 2500 1600 1600 1000 950 350 700 400 1100 500 250 750 1200 300 200


Relative Intensities of Elemental Transitions from Hollow Cathode Lamps (continued) Element

Fill Gas

Wavelength (nm)

Holmium

Ne

Indium

Ne

Iridium Iron

Ne Ne

Lanthanum

Ne

Lead

Ne

Lithium Lutetium

Ne Ar

Magnesium

Ne

Manganese

Ne

Mercury Molybdenum

Ar Ne

Neodymium

Ne

Nickel

Ne

Niobium

Ne

Osmium

Ar

Palladium

Ne

Phosphorus

Ne

Platinum

Ne

Potassium

Ne

Praseodymium

Ne

Rhenium

Ne

Rhodium

Ne

Rubidium

Ne

Ruthenium

Ar

Samarium

Ne

405.393 410.384 303.936 410.176 263.971 248.3271 371.9935 550.134 392.756 217.000 283.3053 670.776 335.956 337.650 356.784 285.213 202.582 279.482 280.106 403.076 253.652 313.259 317.035 463.424 492.453 232.003 341.476 405.894 407.973 290.906 301.804 244.791 247.642 340.458 215.547 213.618 } 214.914 265.945 299.797 766.490 404.414 495.137 512.342 346.046 346.473 343.489 369.236 350.732 780.027 420.180 349.894 392.592 429.674 476.027


Relative Emission Intensitya 2000 2200 500 500 400 400 2400 120 45 200 1000 700 30 25 15 6000 130 3000 2200 14,000 1000 1500 800 300 600 1000 2000 400 360 400 200 400 300 3000 30 20 1500 1000 6 300 100 70 1200 900 2500 2000 200 1.5 80 600 300 600 800


Relative Intensities of Elemental Transitions from Hollow Cathode Lamps (continued) Element

Fill Gas

Wavelength (nm)

Scandium

Ne

Selenium

Ne

Silicon

Ne

Silver

Ar

Sodium

Ne

Strontium Tantalum

Ne Ar

Tellurium

Ne

Terbium

Ne

Thallium

Ne

Thulium

Ne

Tin

Ne

Titanium

Ne

Tungsten

Ne

Uranium

Ne

Vanadium

Ne

Ytterbium

Ar

Yttrium

Ne

Zinc

Ne

391.181 390.749 402.040 402.369 196.09 203.98 251.6113 288.1579 328.068 338.289 588.9950 330.237 330.298 } 460.733 271.467 277.588 214.281 238.578 432.643 432.690 } 431.883 433.841 276.787 258.014 371.791 409.419 410.584 224.605 286.332 364.268 399.864 255.100 255.135 } 400.875 358.488 356.659 351.461 348.937 318.314 318.398 } 385.537 385.584 } 398.799 346.437 407.738 410.238 414.285 213.856 307.590

Relative Emission Intensitya 3000 2500 1800 2100 50 50 500 500 3000 3000 2000 40 1000 150 100 60 50 110 90 60 600 50 40 50 70 100 250 600 600 200 1400 300 200 200 150 600 200

2000 800 500 600 300 2500 2500

Note: These data were obtained using Westinghouse HCLs and a single experimental setup. No correction has been made for the spectral response of the monochromator/photomultiplier tube system. These data were taken from Reference 2. a The most intense line is the Mn 403.076 transition with a relative intensity of 14,000.



INERT GASES In AAS, the excitation source inert gas emission offers a potential background spectral interference. The most common inert gases used in hollow cathode lamps are Ne and Ar. The data taken for this table and the other tables in this book on lamp spectra are from HCLs; however, electrodeless discharge lamps emit very similar spectra. The emission spectra for Ne and Ar HCLs and close lines that must be resolved for accurate analytical results are provided in the following four tables. This information was obtained for HCLs and flame atom cells and should not be considered with respect to plasma sources. In the “Type” column, I indicates that the transition originates from an atomic species and II indicates a singly ionized species.



Neon Hollow Cathode Lamp Spectrum Wavelength (nm) 323.237 330.974 331.972 332.374 332.916 333.484 334.440 335.502 336.060 336.9908 336.9908 } 337.822 339.280 341.7904 344.7703 345.4195 346.0524 346.6579 347.2571 349.8064 350.1216 351.5191 352.0472 356.850 357.461 359.3526 360.0169 363.3665 366.407 369.421 370.962 372.186 404.264 533.0778 534.920 540.0562 576.4419 585.2488 588.1895 594.4834 597.4627 597.5534 } 602.9997 607.4338 609.6163 614.3063 616.3594

Type

Relative Intensitya

II II II II II II II II II I II

5.4 2.8 8.7 28 1.7 5.2 17 3.5 1.7 7.8 17

II I I I I I I I I I I II II I I I II II II II I I I I I I I I I

8.3 16 12 15 6.6 12 12 2.9 3.8 3.6 61 7.8 5.9 19 3.5 3.6 1.9 3.5 4.9 3.1 1.4 1.6 1.6 3.3 2.3 100 8.7 14 2.6

I I I I I

2.8 11 15 20 5.2

Note: These data were taken with a Varian copper HCL operated at 10 mA. The Cu 324.7-nm transition was a factor of 2.9 more intense than the 585.249-nm Ne transition. The spectrum was taken with an IP28 photomultiplier tube (PMT). The relative intensities were not corrected for the instrumental/PMT response. These data were taken from Reference 2. a These data are referenced to the Ne transition at 585.2488 nm, which has been assigned the value of 100.



Neon Lines That Must Be Resolved for Accurate AAS Measurements Analyte Element

Wavelength (nm)

Chromium Chromium Chromium Copper Dysprosium Gadolinium Gadolinium Lithium Lutetium Niobium Rhenium Rhenium Rhenium Rhodium Rhodium Ruthenium Scandium Silver Sodium Sodium Thulium Titanium Titanium Titanium Uranium Uranium Ytterbium Zirconium Zirconium

357.869 359.349 360.533 324.754 404.597 371.357 371.748 670.776 335.956 405.894 346.046 346.473 345.188 343.489 369.236 372.803 402.369 338.289 588.995 589.592 371.792 337.145 364.268 365.350 356.660 358.488 346.436 351.960 360.119

Neon Line (nm)

Required Resolution (nm)a

357.461 359.3526 360.0169 323.237 404.264 370.962 372.186 335.502 in 2nd order is 671.004 336.060 404.264 346.0524 346.6579 345.4195 344.7703 369.421 372.186 404.264 337.822 588.1895 588.1895 372.186 336.9808 and 336.9908 363.3665 366.407 356.850 359.3526 346.6579 352.0472 360.0169

0.20 0.002 0.26 0.75 0.17 0.20 0.22 0.11 0.05 0.82 0.003 0.11 0.12 0.64 0.09 0.31 0.94 0.23 0.40 0.70 0.19 0.08 0.45 0.53 0.09 0.43 0.11 0.04 0.05

Note: These data were taken from Reference 10. a The monochromator settings must be at least one half of the separation of the analyte and interferant transition.



Argon Hollow Cathode Lamp Spectrum Wavelength (nm)

Type

294.2893 297.9050 329.3640 330.7228 335.0924 337.6436 338.8531 347.6747 349.1244 349.1536 350.9778 351.4388 354.5596 354.5845 355.9508 356.1030 357.6616 358.1608 358.2355 358.8441 360.6522 362.2138 363.9833 371.8206 372.9309 373.7889 376.5270 376.6119 377.0520 378.0840 380.3172 380.9456 383.4679 385.0581 386.8528 392.5719 392.8623 393.2547 394.6097 394.8979 397.9356 399.4792 401.3857 403.3809 403.5460 404.2894 404.4418 405.2921 407.2005 407.2385 407.6628 407.9574 408.2387 410.3912 413.1724 415.6086 415.8590

II II II II II II II II II II II II II II II II II II II II I II II II II II II II II II II II I II II II II II II I II II II II II II I II II II II II II II II II I


Relative Intensitya 3.5 1.9 1.5 1.5 2.2 2.2 1.8 3.7 2.0 7.2 7.0 4.0 11 12 16 1.8 11 3.9 8.5 1.2 2.0 1.3 3.3 5.5 1.3 9.8 5.1 6.8 1.7 4.0 5.5 1.8 2.6 1.2 7.0 9.9 6.9 3.2 14 5.2 5.6 6.2 4.3 2.5 2.3 1.6 9.0 21 34 5.5 2.0 4.4 3.2 10 61 2.4 1.4


Argon Hollow Cathode Lamp Spectrum (continued) Wavelength (nm)

Type

416.4180 418.1884 419.0713 419.1029 419.8317 420.0674 421.8665 422.2637 422.6988 422.8158 423.7220 425.1185 425.9326 426.6286 426.6527 427.2169 427.7528 428.2898 430.0101 430.0650 430.9239 433.1200 433.2030 433.3561 433.5338 434.5168 434.8064 435.2205 436.2066 436.7832 437.0753 437.1329 437.5954 437.9667 438.5057 440.0097 440.0986 442.6001 443.0189 443.0996 443.3838 443.9461 444.8879 447.4759 448.1811 451.0733 452.2323 453.0552 454.5052 457.9350 458.9898 459.6097 460.9567 462.8441 463.7233 465.7901 470.2316

I I I I I I II II II II II I I I II I II II I II II II II I I I II II II II II II II II II II II II II II II II II II II I I II II II II I II I II II I


Relative Intensitya 4.4 6.9 9.1 8.9 38 38 2.2 4.3 5.6 12 15 2.3 42 11 7.4 18 100 2.5 13 3.3 6.6 17 4.2 12 5.8 3.7 1.5 5.4 3.3 9.6 32 6.5 10 20 6.7 5.7 15 1.6 1.2 5.4 5.3 5.3 7.9 19 33 20 2.0 3.2 1.3 1.4 47 1.8 1.3 1.4 5.5 1.9 2.5


Argon Hollow Cathode Lamp Spectrum (continued) Wavelength (nm)

Type

472.6868 473.2053 473.5906 476.4865 480.6020 484.7812 486.5910 487.9864 488.9042 490.4752 493.3209 496.5080 500.9334 501.7163 506.2037 509.0495 514.1783 514.5308 516.2285 516.5773 518.7746 522.1271 545.1652 549.5874 555.8702 557.2541 560.6733 565.0704 588.8584 591.2085 592.8813 603.2127 604.3223 611.4923 617.2278 696.5431 706.7218 738.3980 750.3869

II II II II II II II II II II II II II II II II II II I II I I I I I I I I I I I I I II II I I I I

Relative Intensitya 43 9.7 1.3 1.5 36 1.6 1.3 58 11 3.5 4.1 28 5.5 12 5.9 2.9 5.7 3.7 3.8 1.8 3.8 1.2 1.7 3.1 4.0 1.9 4.9 1.7 1.9 4.1 1.4 4.1 1.6 2.2 1.1 3.2 1.7 1.2 2.7

Note: These data were taken from an Ar-filled Ga HCL at the Los Alamos Fourier Transform Spectrometer facility.11 a

These data are referenced to the Ar transition at 427.7528 nm, which has been assigned the value of 100.



CLOSE LINES FOR BACKGROUND CORRECTION In AAS, it is possible to make background corrections in many cases by measuring a normally nonabsorbing transition near the analytical transition. This table presents a list of suitable transitions for such a background measurement. It is often desirable to check the background absorbance by more than one method even if there is a built-in background measurement by some other means such as the continuum or Zeeman methods. In the table below, the first two columns give the analyte element and wavelength of the analytical transition, and the last two columns give the transition useful for the background measurement and its source. If the source is Ne and the HCL is Ne filled, the same HCL can be used for the background measurement; if not, a different HCL must be placed in the spectrometer to make the measurement. Close Lines for Background Correction Element

Analysis Line (nm)

Aluminum Antimony Arsenic Barium

309.2711 217.581 231.147 193.759 553.548

I I I I I

Beryllium Bismuth Bromine Cadmium Calcium Cesium Chromium

234.861 223.061 306.772 148.845 228.8022 422.673 852.1122 357.869

I I I I I I I I

Cobalt Copper Dysprosium

204.206 324.754 421.172

I I I

Erbium Europium Gallium Gold

400.796 459.403 287.424 242.795

I I I I

Indium Iodine Iron Lanthanum

303.936 183.038 248.3271 550.134

I I I I

Lead Lithium Magnesium

283.3053 217.000 670.791 285.213

I I I I

Manganese Mercury Molybdenum Nickel

279.482 253.652 313.259 232.003

I I I I


Background Line (nm) 306.614 217.919 231.398 191.294 540.0562 553.305 557.742 235.484 226.502 306.614 149.4675 226.502 421.9360 423.5936 854.4696 352.0472 358.119 238.892 242.170 324.316 421.645 421.096 394.442 460.102 283.999 283.690 242.170 306.614 184.445 249.215 550.549 548.334 280.1995 283.6900 220.3534 671.7043 283.690 283.999 282.437 280.1995 249.215 312.200 232.138

I I I II I I I I II I I II I I I I I II I I II I I I I I I I I I I I I I II I I I I I I II I

Source Al Sb Ni As Ne Mo Y Sn Cd Al N Cd Fe Fe Ne Ne Fe Co Sn Cu Fe Ag Er Cr Sn Cd Sn Al I Cu Mo Co Pb Cd Pb Ne Cd Sn Cu Pb Cu Mo Ni


Close Lines for Background Correction (continued) Element

Analysis Line (nm)

Palladium Phosphorus Potassium Rhodium

247.642 213.618 766.490 343.489

I I I I

Rubidium Ruthenium Selenium Silicon Silver

780.027 249.894 196.09 251.6113 328.068

I I I I I

Sodium Strontium Tellurium Thallium

588.9950 460.733 214.281 276.787

I I I I

Tin Titanium Uranium

224.605 286.332 364.268 365.350 358.488 318.398 318.540 213.856

I I I I I I I I

Vanadium Zinc

Background Line (nm) 249.215 213.856 769.896 767.209 350.732 352.0472 778.048 352.0472 199.51 249.215 332.374 326.234 588.833 460.500 213.856 217.581 280.1995 226.502 283.999 361.939 361.939 358.119 324.754 324.754 212.274

Note: These data were taken from Reference 12.


I I I I I I I I I I II I I I I I I II I I I I I I II

Source Cu Zn K Ca Rh Ne Ba Ne Se Cu Ne Sn Mo Ni Zn Sb Pb Cd Sn Ni Ni Fe Cu Cu Zn


BETA VALUES FOR THE AIR–ACETYLENE AND NITROUS OXIDE–ACETYLENE FLAMES Beta values represent the fraction of free atoms present in the hot flame gases of the flame indicated. These values have been taken from various sources and were either experimentally measured or calculated from thermodynamic data using the assumption of local thermodynamic equilibrium in the flame. These values do not have very good agreement within each element; however, the values do provide an indication of the probable sensitivity of the particular flame. Beta Values for the Air–Acetylene and Nitrous Oxide–Acetylene Flames Element

Symbol

Beta A/AC Flame

Aluminum

Al

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